WO2007033896A1

WO2007033896A1 - Method for producing a container with a drag plunger by multi-component injection moulding

Info

Publication number: WO2007033896A1
Application number: PCT/EP2006/065932
Authority: WO
Inventors: Bernhard Felten
Original assignee: Beiersdorf Ag
Priority date: 2005-09-22
Filing date: 2006-09-01
Publication date: 2007-03-29
Also published as: EP1943077A1; DE102005046568A1

Abstract

Method for producing parts for a single- or multi-chamber dispensing system (1), the dispensing system comprising at least one container (10), which has one or more chambers, a displaceable plunger (12) in each container chamber and at least one pump head (13), with which the content can be discharged from the container chamber or chambers, and parts of said system being produced by 2- or multi-component injection moulding, characterized in that in a first step a container is injection-moulded from a first material, in a second step a part (5) of the injection mould is retracted (core retracting technique) or exchanged (turning plate technique) and in a third step the plunger is produced by injecting a second material into the cavity produced by the second step, the circumferential contour of the piston being made to match to the circumferential contour of the inner container wall.

Description

description

METHOD FOR PRODUCING A CONTAINER WITH TOWING PISTON IM

MULTI-COMPONENT INJECTION

The invention relates to containers with trailing piston and a method for producing containers with trailing piston.

Dispenser systems are known in the art. In particular, so-called airless systems with drag pistons are widespread.

Dispensing systems with drag pistons enjoy great popularity, especially in the cosmetics industry. They have, among others, the following advantages:

- Removed filling volume is not replaced by air, thereby also for oxidation-sensitive preparations used, outer shape is maintained throughout the period of use, container is not under pressure and easy dosage possible.

A major disadvantage is the sometimes complicated structure compared to other packaging materials such as tubes or crucibles.

The aim of the invention is therefore to provide dispenser systems whose production costs are reduced compared to the conventional production method, but whose filling and use are in no way inferior to the currently customary dispensers.

In the system of Fa. Josef Wischerath (Pulheim, DE 197 41 957), the dispenser consists of a cylindrical or oval or elliptical container with vertical walls. It is open at the top and has a sealing surface and a snap edge. In this container, a piston with the same cross-section is inserted and pushed to the bottom of the container. So that the air displaced by the piston can escape, a venting opening available. The container is delivered with the inserted piston to the filling operation. There, the contents are filled and the container top sealed with a pump head. This has corresponding mating surfaces for sealing and also the contrary snap edge to ensure a tight and firm connection. When the pump is actuated by pressing vertically, the trapped small amount of air is first pumped out. Subsequently, the filling material is applied, which can have a consistency from watery to pasty. The discharged volume creates a negative pressure in the Füllgutraum, which is compensated by a movement of the piston upwards. The advantages of this type of packaging for the consumer are the easy and convenient metering of the contents and a pollution-proof storage, as nothing gets into the container. In addition, the low load with atmospheric oxygen for some contents of advantage.

In the case of the dispenser system from Megaplast Dosiersysteme (Villingen-Schwenningen, DE 295 06 682 and DE 37 19 252), the pump housing and the container form one unit and the filling takes place from "below." After filling, a piston is used to hold the container at its end It is pressed down to the contents, so that the air can escape under the piston, this piston has a vent hole.On the piston has reached its position, this opening is closed with a plug.The function corresponds to the system described above ,

So far, the pistons are produced individually by injection molding and then, either before or after filling, inserted into the container. During injection molding, molten thermoplastic material is injected into a mold, usually made of steel, which corresponds to the negative of the part to be produced. This steel mold is cooled so that the liquid injected plastic solidifies, then the steel mold is opened and the molded part is ejected. After closing, the production cycle can start again.

The separate production of container and piston means three production steps, namely

1. separate injection molding of the piston,

2. separate injection molding of the container and

3. the insertion of the piston, All parts must be stored, sorted and traded.

Since the accuracy of fit between the container and piston is very important, similar shapes must produce precision parts of high quality and dimensional accuracy. This causes high costs.

The object of the invention described below is to provide a dispensing system and a method for producing the dispenser system according to the invention with which the abovementioned deficiencies are remedied.

This object is achieved by a method for producing parts for a single or multi-chamber dispenser system, wherein the dispenser system at least

a container having one or more chambers, a displaceable piston in each container chamber and at least one pump head, with or with which the contents of the one or more

Has container chambers brought out;

includes and parts thereof in 2- or multi-component injection molding, characterized in that

in a first step, a container of a first material is injected,

in a second step, a part of the injection mold is retracted (core retraction technique) or exchanged (insert technology) and in a third step the piston is made by injecting a second material into the cavity created by the second step, the peripheral contour of the piston being the peripheral contour of the inner container wall is adjusted.

In the method according to the invention, the container and the piston are produced quasi as a part in the so-called 2- or multi-component injection molding process.

In this method, after injection and solidification of the plastic, either a part of the shaping contour is withdrawn (core retraction technique, core back technique) or the one half, which exchanges the contour determining shape (turning plate technique). Subsequently, it is injected into a second plastic component forming the piston. ever After compatibility of the two plastic components, the two successively produced parts are either intimately connected (welded) or remain separated from each other by incompatibility and / or already done strong cooling. This "separation" has as a side effect that the second contour is a precise impression of the first one, which should be used for the production of the containers and pistons.

The following list contains preferred injection molding materials that can be used by blending with additives in the process according to the invention:

Particularly suitable are polypropylene and polyethylene, as they are very inexpensive and easy to work with.

In order to achieve a separation of the injection molded parts, it is expedient to use different materials for pistons and cups. Compatibilities and incompatibilities are known and z. B. in the publication "Technology by Engel" the Engel Vertriebsgesellschaft mbH, A - 4311 Schwertberg reproduced.

When using the same materials for pistons and containers, it is possible to achieve a separation of the parts by controlled cooling, suitable process control and addition of release agents.

Crystallization accelerators or amorphous injection molding materials allow the shrinkage process to be controlled and utilized to adjust the piston oversize.

In the following, the method according to the invention and the dispenser device obtainable thereby will be described on the basis of performance examples. However, the invention should not be limited to the embodiments, which serve only to visually support the description.

Figures 1 to 9 show schematically the process steps for the production and filling of a dispenser system according to the invention. Figures 10 to 12 represent possible cross-sectional shapes of dispenser systems made according to the invention. The illustrations serve in particular to explain the invention.

Show it

Figure 1: Syringing the cup of top-loading dispensing systems Figure 2: Syringing the top-dispensing system of dispensers Figure 3: Example of a dispenser made by the inventive process with partially closed container bottom and vent Figure 4: Syringing the cup of bottom-loading dispenser systems Figure 5: Syringing the piston of bottom-loading dispenser systems Figure 6: Pulling out (a) or pushing (b) the piston before filling Figure 7: Blowing out of the piston Figure 8: Filling through filling mandrel Figure 9: Example of a dispenser produced by the inventive method without container bottom

Figure 10: different producible by the inventive method piston shapes

Figure 1 1: selected cross sections of the container shapes that can be produced by the method according to the invention

Figure 12: selected cross-sections of producible with the inventive method multi-chamber containers

Figures 1 to 1 1 contain, among other parts, the following elements:

1 dispenser containing container, piston and pump head

2 mold base (mold half injection side)

3 mold top (tool half ejector side)

5 inner shape (core)

6 injection point 1. component (for container)

7 injection point 2nd component (for pistons)

9 cones

10 containers

1 1 bottom opening (vent opening)

12 pistons

13 pump head

14 snap rim on the pump head

15 snap rim on the container

16 container neck

17 piston opening

18 product room

20 contents

21 drawbar 22 push rod

23 Blowing pin

24 filling mandrel

25 plugs

In the first step (Figure 1), the cup-like container (10) is molded by injecting thermoplastic material through the injection point (6) into a mold containing a mold bottom (2), a mold top (3) and an interior mold (5) , The bottom opening (1 1) is formed by the injection point (7) of the second component (for the piston).

After a cooling time, in which the first component has reached a sufficient strength, in a second step (Figure 2), the inner mold (5), which forms the inner wall of the cup, pulled out a piece and into the cavity, which thereby in the area of the cup bottom, a second component forming the piston (12) is injected through the injection point (7). The piston (12) corresponds exactly to the container cross-section and is already "mounted".

The result is a donor (1) as shown in Figure 3.

According to the invention is also a multi-part structure of the mold, which forms the inner wall and different motion vectors of the individual mold parts. This allows you to create optimized piston geometries (see Figure 12).

Through skillful process control and choice of material, the piston clearance and contact pressure of the piston can be adjusted to the vessel wall. A slight excess of the piston relative to the container inner diameter contributes to a good seal of the piston, but still allows a low-friction movement.

In Figures 1 and 2, the top edge of the container where the pump head is attached is not detailed. According to the invention, the connection to the pumphead can be made by a snap rim (as described in DE 197 41 957), a screw connection, gluing or by welding. From the prior art, other possible solutions are known. Bottom-fill dispensers can also be made by a modification of the two-component injection molding technique described above (see Figures 4 and 5). For this purpose, in the injection-side mold half (2) a pin (9) protrude into the inner mold (5). By this an opening in the cup (10) and piston (12) is formed during injection molding.

The smallest diameter of the opening is technically conditioned and depends on the diameter of the second injection point (7). According to the invention, the opening can reach the inner diameter of the container neck (16).

In order to prevent slipping out of the piston, it is in the context of the invention to form pins, nubs, grooves, rings, beads or the like at the lower edge of the container. Likewise, the container bottom can be screen-like or grid-like.

However, since the piston remains in the upper position with the piston produced in this way, there is no filling space. Nevertheless, to ensure the filling, there are the following possibilities:

According to the invention, in a step subsequent to injection molding, prior to assembly of the pump head (13), the piston is pushed through the container neck (16) by pushing with a push rod (22) (Figure 6b) or by pulling with a piston opening (17) Pull rod (21) "from below" (Figure 6a) into a starting position.

Likewise, according to the invention, after the pump head (13) has been mounted, the piston (12) is moved by a blowing mandrel (23) into a position close to the container bottom so that a correspondingly large filling space (18) is created (FIG. 7). ,

It is particularly advantageous to fill the container (10) with a filling mandrel (24) through the opening (17) in the bottom of the piston (Figure 8). It is advantageous if the Fülldorn seals the opening in the basket all around. In order to achieve a bubble-free filling, it is advantageous to move the filling mandrel back in synchronism with the piston.

In a last step, a plug (25) is introduced into the bottom of the piston (12), which then seals the filling opening (Figure 9). In order to achieve a better seal and lower frictional resistance of the piston in the container, it is advantageous if the piston is not disc-shaped as a flat cylinder, but the piston edge has an acute-angled contour. Examples of advantageous piston shapes are shown in FIG. According to the invention, the upper and lower sides of the piston and the container bottom have the same contour, since they are formed by an axial displacement of the inner mold (Figure 10a).

When using the insert technology, pistons can be produced which have the same contour on the side facing the container bottom as the container bottom and form a second contour on the side facing away from the container bottom (FIG. 10 b).

By the method according to the invention it is also possible to produce dispensing systems which have an outer contour deviating from round or oval. In this case, the outer shape of the injection mold and the inner core in cross-section on the later present in the container contour.

The complicated geometries of the cross-sectional area and thus the container shape, which are permitted by this method, thus provide new possibilities for differentiating products, especially in the cosmetics sector.

One of the unlimited number of possible container cross-sectional shapes is reproduced as a horizontal cross-section in Figure 1 1.

As a further advantage of this manufacturing process offers a cheap way to realize multi-chamber dispenser. Dispenser systems are known with two parallel, cylindrical chambers, but meet only limited aesthetics claims. With the method according to the invention it is possible to produce sophisticated Mehkammerbehäter. Figures 12 a) to c) represent cross-sections of two-chambered containers in which the chambers are side by side (Figure 12a), one inside the other (Figure 12b) or "interlocked" (Figure 12c), and this selection should not be taken as limiting. Figure 12d), on the other hand, shows a possible cross-section through a three-chamber container, with the numbers I to II and I, respectively. In the conventional donor production in which container and piston are made separately, it is possible only with great effort to produce deviating from the circle donor, since the positioning of the piston relative to the container must be very accurate, otherwise the piston is not in insert the container. For non-rotationally symmetric shapes, this is currently only possible by hand.

According to the invention, the pump can have its suction point exactly between the two or more chambers and at the same time convey the contents out of all the chambers at the same time. Likewise, a plurality of intake passages may be present, so that the chambers are also sealed against each other. Also the attachment of two or more independent pumps is possible, whereby the pumps can be operated simultaneously or separately.

It is also within the meaning of the invention to inject the piston in a first step and then insert it into the container tool and then, in a second step, to overmold it. As a result, as with the insert technology, there is no longer the restriction that the top and bottom of the piston must correspond to each other. However, it remains the exact impression of the contact surfaces and thus the sealing surfaces.

Another variation of the invention is to make the piston from two materials. It may be advantageous to make the sealing area of a soft and high quality material (eg TPE based on EPDM / PP) and the actual piston of a more favorable material (eg PE). According to the invention, a 2-component piston can also be produced integrally in the tool.

Claims

claims

A method of manufacturing parts for a single or multi-chamber dispensing system, wherein the dispensing system is at least one

a container having one or more chambers, a displaceable piston in each container chamber, and at least one pump head, with or with which the contents can be carried out of the container chamber (s),

and parts thereof are produced in 2- or multi-component injection molding, characterized in that

in a first step, a container of a first material is injected, in a second step, a part of the injection mold withdrawn (nuclear retraction technique) or exchanged (insert technology) and in a third step, the piston by injecting a second material in the resulting by the second step Cavity is produced, wherein the circumferential contour of the piston of the peripheral contour of the inner container wall is adjusted.

2. The method according to claim 1, characterized in that the piston includes a closable opening which can be used for positioning of the piston in the region of the container bottom and for filling.

3. The method according to at least one of the preceding claims, characterized in that the container and piston are made of the same materials.

4. The method according to at least one of the preceding claims, characterized in that the container and piston are made of different materials.

5. The method according to at least one of the preceding claims, characterized in that the container is filled through the opening in the piston.

6. The method according to at least one of the preceding claims, characterized in that the container from above, through the opening, which is later closed by the pump head, is filled.

7. The method according to at least one of the preceding claims, characterized in that the cross section from the container foot to the container neck is the same, but the contour of the cross section has an irregular or non-rotationally symmetrical shape.

8. The method according to at least one of the preceding claims, characterized in that the contour of the horizontal piston cross section has the same contour as the container, but has a certain excess.

9. The method according to at least one of the preceding claims, characterized in that the piston has the same contour on the top and bottom.

10. The method according to at least one of the preceding claims, characterized in that the piston on the top and / or bottom has the same contour as the bottom of the container.

1 1. A method according to at least one of the preceding claims, characterized in that the edge region of the piston is elastic and / or flexible and / or made of a different material than the inner region.