DE2417173A1 - CONTAINER CLOSURE WITH SEAL - Google Patents

Description

Container closure with seal

The invention relates to seals for container closures, in particular with threaded closures.

Container closures are therefore primarily provided with seals to prevent air from entering the container and / or to prevent the loss of the contents of the container to the outside. They are particularly important in the closures of containers in which Food or drink is kept because food or drink is contaminated in a container can lead to serious damage to health through the entry of air before consumption. An essential area of application of closures provided with seals are the bottle closures.

So that the customer can close the container again after opening it it is desirable to have a threaded fastener to use, which can be removed by unscrewing

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can. A common type of coiled locks, which has found widespread commercial adoption is of the in situ threaded type: the threads are formed on the container during the closure of the closure. An initially unthreaded Closure is applied to the neck of a threaded container and, under pressure, the thread is applied to the Neck of the container embossed in the closure. For example, the threads can be formed with the aid of a roller. A A well-known closure of this type is the "roll-on" bottle closure. Various other roller threaded closures such as "Flavorlok" (Metal Closures Ltd., GB-PS 975 739) and "Coronet" (The Metal Box Company Ltd., GB-PS 1,054,295). In the following should the in situ threaded closures as I.S. closures are designated.

Seals for threaded closures are often made using the so-called "spin-line" process. A certain amount of a polyvinyl chloride plastisol is used here calibrated in a closure and the closure at high speed around its central axis rotates so that the plastisol is distributed by centrifugal force, and the plastisol then caused to flux in the closure will. The plastisol is a viscous dispersion of

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Polyvinyl chloride in a plasticizer. It is softened by heating it to a temperature at which the plasticizer degrades Polyvinyl chloride is absorbed and forms a homogeneous mass, which on cooling turns into a rubber-like solid stiffens.

The "spin-line" process has, in spite of its economical nature Success only limited areas of application. One limitation is that the shape of the seal is not critical can be changed. Since the molding is effected by centrifugal forces, the seals produced will thicken gradually from the center of the closure towards the periphery of the closure. Since in general different Seal shapes are optimal for various closures or containers, there is one major limitation the "spin-line" process in that other shapes are not manufactured can be. Another problem with the "spin-line" process is that it is difficult in large-scale production is to introduce the seal-forming material symmetrically in the central region of the closure, which results in that when rotating the closure, the sealant is not evenly distributed in the desired shape.

The invention relates to new seals which are suitable for use in various threaded closures are, and conditions under which it is possible to make seals

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in closures made from a solid tablet of vinyl chloride polymer resin to melt.

One object of the invention is to propose threaded container closures and I.S. screw closures, which have a seal which is made before the deformation, that is to say before the bottle is closed with the closure an essentially flat central area and an adjoining peripheral area, the thickness of which is everywhere is larger than that of the central area and which increases continuously and / or gradually in a radially outward direction the edge of the closure increases.

If the closure is with the opening facing up, the peripheral part of the seal extends into a region of the edge of the closure, which is higher than the central area. From the center of the clasp the height of the peripheral increases Area with respect to the central area and then increases further or remains the same or increases over part of the radial distance and then remains the same for the rest of the distance. This embodiment can also be referenced can be described on the gradient of the peripheral area. In the radially outward direction, the peripheral area has an initially positive gradient which then becomes zero or remains positive.

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The p_erifere area of the seal can also have an edge area have, which is approximately parallel to the edge of the container closure reaches up.

Bg-i. one embodiment of the invention takes the peripheral Beareich continuously, preferably with the same gradient, iir. ra'di aler direction towards the closure edge or up to one.- stage, which forms the edge area of the seal. At a Another embodiment of the invention is the peripheral Area a step that extends radially outwards either up to Vergehlußrand or up to a second stage that extends forms the edge area of the seal.

Further embodiments according to the invention are based on cowardly figures explained in more detail.

Figr. 1 is the cross section through one with the invention Gasket provided closure and a molding that can be used for molding.

Fig :. Z to 7 are cross sections through seals provided with seals according to the invention.

Figures 8-10 are cross-sections through closures which are different have formed seals.

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Figures 11 to 13 are cross-sections through gaskets Closures, which in turn are another embodiment illustrate the invention.

Figures 14 and 15 are schematic diagrams of devices for forming the seals.

16 and 17 are cross sections through bottle caps "Coronet" and "Flavorlok".

In FIGS. 3 to 13, 16 and 17, for reasons of space saving reproduced only the area of the closure in which the seal is located. The lock heights are the same as in Fig. 2.

In Fig. 1 an inverted bottle cap is shown before being applied to a bottle. she consists from a main area 1 and an edge 2. The seal 3 consists of a substantially flat central area 4 and a peripheral area 5, which has a bend 6 upwards and in a radially outward direction. This bend 6 becomes reproduced planar, but it can also have a concave or convex shape. The distance between the center of the Closure and the incipient lifting of the peripheral area of the seal is represented by χ and the angle between the rise 6 and the flat area 4 or 1 with

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ß. The broken lines in the figure are geometric Guidelines. In Fig. 1, a part of a corresponding molding device 7 is also shown, wherein the molding surface a flat central area 8, which corresponds dimensionally to the central area 4 of the seal, and peripheral Has areas 9 which correspond to the peripheral areas 5 of the seal. The corner areas 10 of the seal and the corresponding Corner areas 11 of the molding device are preferably slightly curved to allow for a more gradual change in the Profile between area 4 and the peripheral area 5.

The angle ß can be 20 to 80; it has been found that an angle of about 30 especially for "Flavorlok" caps suitable is. These angle values are suitable for seals in which the peripheral areas have a constant gradient from the corner of the central area to the edge, and for those where the peripheral area is a single step has, which connects to the edge of the closure and from the corner of the central area to the beginning of the stage has constant gradient. The step preferably corresponds to 0.1 to 50% of the radial length of the peripheral area, preferably 5 to 20%.

The distance X is typically from 0.25d to 0.45d, where d is the maximum inner diameter of the closure.

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Good closure properties were achieved with "Flavorlok" closures obtained in which X. in the seals was about 0.37 d to 0.42 d. A particularly preferred group of those according to the invention Seals are those in which the thickness is constant from the edge of the central area to the edge of the closure or rises to the beginning of a flat area at the edge, v / obei ß is about 20 to 80 °, preferably 25 to 50 °, X is about 0.25 d to 0.45 d, preferably 0.37 d to 0.42 d, and where, if the edge is followed by a flat area, the radial length of which is 0.1 to 50%, preferably 5 to 20% of the radial length of the peripheral region.

In general, the embossing tool will normally be slightly narrower than the inner diameter of the closure, so that some clearance remains for entry into the closure during molding. In Figures 2 to 13 are reproduced closures provided with seals. In Figures 2 to 4 seals for "Flavorlok" caps with an inner diameter of 2.67 cm, while Figures 5 to 10 "Coronet" caps with a maximum reproduce inner diameter of about 2.67 cm. The seals according to Figures 2 to 7 have the following ß and X values:

figure No. 2 3 4th 5 6th 7th angle ß: 30th 30th 45 30th 30th 45

Distance x: 0.4Od O, 37d O, 38d O, 385d O, 37d O, 37d

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The seals according to FIGS. 8 to 10 have the distances χ = 0.34 d, 0.31 d and 0.33 d.

The corners labeled P and R in FIGS. 2 to 4 and 8 to 10 can be sharp or rounded. In Fig. to 4 the radius of the curvature at P (the beginning of the peripheral area) is 0.25 mm. In Figures 8 and 9 is the radius of the curvatures at P and R. 0.25 and 0.51 mm; in Fig. 10 0.25 mm. The curvature at these points is wide Boundaries changeable.

In FIGS. 8 and 10, the height (h) of the peripheral area of the seals can depend on the type of closure and the container can be changed. In Figures 8 to 10 it is about 1.0 mm.

A second embodiment according to the invention is shown in FIGS described, with the peripheral area of the seals consists of a step which has a flat or raised area, the radial length of which is 65 to 98% of the radial Length of the peripheral area.

• In Figures 11 to 13 the distances are χ 0.36 d, 0.32 d and 0.36 d, while the heights of the annular ribs are 1.6, 2, 0 and 2.0 mm.

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Essentially two molding processes are suitable for producing the seals according to the invention. On the one hand, there is "cold forming", which is also the subject of the British patent of applicant 1,112,023 and corresponding patents and applications in other countries. A solid insert of the material forming the seal, for example a tablet, is placed in a closure which is preferably preheated in order to glue the insert in the closure. Then the closure is heated to a temperature above the softening point "of the seal-forming material, for example on a hot plate or in an oven, and the seal is formed by a molding device, the surface of the molded part by continuous or temporary cooling with a liquid coolant at a temperature below the softening point of the sealing material is maintained. the temperature of the molding surface is preferably maintained at temperatures below 100 C. when using polyvinyl chloride, a temperature of 5 to 25 ° C, in particular from about 10 ⁰ C is very suitable. the closure may if necessary during the Deforming can be heated on a hot plate.

The second forming process is "hot forming", which differs from the process described above / that the mold is either not cooled with a liquid coolant or is actually heated. The table or

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the plate is also preferably heated. This procedure is not particularly suitable for some sealing materials, such as blends of polyethylene with butyl rubber; however, plasticized polyvinyl chloride can be molded in this way. Solid plasticized Polyvinyl chloride is a material that has already gelled and that, when gelled, turns out to be a normal thermoplastic behaves. It can be heated to its softening point. Good results have been obtained with seals at about 160 ° C. Temperatures in the range from 150 to 170 ° C are generally suitable temperatures for both the mold and the table. At these temperatures is the holding time, i.e. the dwell time of the mold in contact with the sealing material, is relatively long, for example 3 to 6 seconds, and depends on the temperature. A long hold time is to soften the top and bottom Desired lower areas of the tablet made of polyvinyl chloride by prolonged contact with the relatively hot mold.

The pressure exerted by the mold when hot forming

can be relatively low, for example 28 kg / cm.

Usually it is no smaller than 4.9 kg / cm or larger

ο
than 140 kg / cm.

Both molding methods are particularly useful for forming seals threaded and I.S.

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generally suitable, regardless of the special form and training the seal. PVC seals can be formed in crown corks under the conditions described.

The seals provided with seals according to the invention are preferably made from plasticized polyvinyl chloride, since this is a material that is recognized as being useful as a sealing material. Softened Polyvinyl chloride is normally introduced into the closure as a tablet, which is usually smaller in diameter than that of the shutter. The use of solid plasticized polyvinyl chloride has over the use of a Plastisols have numerous benefits. One advantage is that a suspension grade PVC resin is used instead of a emulsion grade resin normally used in plastisols can be used. The former does not contain any Emulsifier. Some emulsifiers affect polyvinyl chloride in such a way that a seal made from it is uncomfortable can affect the taste of a bottled beverage. Therefore it is an advantage to have a resin from Use suspension purity. Another advantage is that the tablets are right in the center of the closure can be introduced, whereby a more precise placement of the sealing material than achieved with the "spin-line" method will. Another advantage is that the fixed

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Tablets conveniently by cutting. From an extruded rod can be obtained. Such a stick is easier to handle than plastisols. While plastisols have a certain viscosity must have, which must be neither too high nor too low, is the use of an extruded rod, for example much less problematic, so that very different sealing materials can be used.

Plasticized polyvinyl chloride can of course contain any or some of the usual additives such as stabilizers, Pigments, fillers, lubricants, lubricants and the like. The type of plasticizer is not critical. Diisooctyl phthalate or any of the other known plasticizers can be used. When producing the invention In addition to PVC, seals can also be used with a large number of other seal-forming materials, such as, for example in GB-PS 1 112 023, 1 112 024 and 1 112 025 to be discribed. In general, polyethylene / butyl rubber mixtures containing 40 to 70% by weight of polyethylene are also used and 60 to 30% by weight of butyl rubber are suitable.

The mixtures are preferably formed by cold forming.

The invention relates to both threaded closures or I.S. closures and the containers with such

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Closures are closed. The I.8. Closures are threaded of course when applied to the container, and the seal is made by pressing against the Brim or rim of the container molded into a different shape.

Never seals according to Figures 2 and 4 are especially designed for closing suitable with the use of "Flavorlok" caps. This type of bolt head is described in GB-PS 975 described. The invention is illustrated in more detail by means of the following examples.

Examples

Using the following compositions C-1 through C-5 suspension grade PVC resin was extruded into 8 mm thick tubes.

Compositions (parts by weight) Components C-I C-2 C-3 C-4 C-5

Cörvic D65 / O2 (PVC resin) 100 100 100 100 100

Diisooctyl phthalate (plasticizer) 55 55 55 60 65 low molecular weight

Polyethylene (lubricant A) - 0.5 -

Paraffin Wax (Lubricant B) - - 0.75 0.75 Vaseline (Lubricant C) - 0.75 0.75 FERRO 76OX (stabilizer) 3 3 3 3 3

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"Corvic D65 / O2" is a suspension grade PVC resin and has a K value of 65. Ferro 76OX is a stabilizer made from calcium / zinc stearate from Ferro UK Limited. All the numbers relate to parts by weight.

example 1

The compositions C-1 to C-4 were tablets produced by cutting off appropriate strands with a weight per tablet of 330 mg and in aluminum RO "Flavorlok" caps (Metal Closures Ltd.) arranged centrally. The tablets were then hot deformed to form the seals as shown in FIG. The device used for this purpose possessed an electrically heated mold and a table that independently heats to any temperature up to 25O ° C could become. Maximum forces of about 150 kg were during

2 of the deformation expended, resulting in a pressure of about 25 kg / cm corresponded. The work was carried out under the following conditions:

Mold temperature 160 C

Table temperature 21O ⁰ C

Hold time 6 seconds

The caps were placed on dry glass (MCA 1 finish) four hours after molding; Immediately after the closure, the torque for unscrewing or unscrewing (unscrewing force) was determined. The results are summarized in the table. < _.0 g _{84 4/0} 3 _{0 6}

Table 1 Unscrewing force (seal according to Fig. 2) Composition of average torque (kg)

C-1 6.3

C-2 7.1

C-3 - 4.7

■ C-4 4.5

Example 2

Compositions C-1, C-3, C-4 and C-5 were made under the above conditions and using the same caps deformed. There were three seals according to FIGS. 2, 3 and 4 and three seals with annular ribs according to FIGS. 11, 12 and 13 made from each of the four compositions and weighed:

Figure 2 330 mg Figure 11 300 mg Figure 3 410 mg Figure 12 310 mg Figure 4 370 mg Figure 13 410 mg

They were measured by determining the weight of the tablet. Tablets of this weight completely fill the space between the mold and the closure cap and form seals, the thickness of the central area 230 being ₇ μm in all six different arrangements. These seals were aged for 24 hours before being applied to dry glass

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became. Then the torque to remove was determined; the results, which are given in Table 2, showed that the lowest torsional forces are obtained with compositions C-1 and C-3.

Table 2 Fig. 11 (in kg) Standard
softness (kg) Fig. 11 8.1 . for hot-formed seals Fig. 11 4.6 2.1 Unscrewing force Seals average
Composition according to unscrewing force Fig. 11 4.5 1.1 Fig. 2 4.9 - 0.9 C-5 Fig. 2 19.0. 0.9 C-1 Fig. 2 5.3 3.6 C-3 Fig. 2 7.2 0.5 C-4 6.8 0.8 C-5 C-1 C-3 C-4

The ability of these closures to close a pressurized container was determined by determining the "vent pressure" certainly. This is the pressure at which a closed cap starts contained in the bottle Allowing gas to escape and is normally determined by passing nitrogen through a hole in the bottom of the with Cap closed bottle, which is immersed in water

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is diving, blowing in. The nitrogen pressure is increased until develop under the cap produces bubbles; the pressure at which this occurs is referred to as the "venting pressure" of the closure cap under the test conditions.

Caps made with compositions C-5, C-1, C-3 and C-4 provided and deformed with molds were placed on glass bottles (MCA 1 finish) using a "Flavorlok" closure head upset. The ventilation pressure was then determined (see Table 3). The results show that only Caps that had seals that are made in accordance with FIGS.

withstood a pressure of more than 7 kg / cm. The seals according to FIG. 3 were less good than those according to FIGS. 2 and 4. It can be assumed that this is because that the points at which the sealing pressure is greatest are different, which in turn is probably a function the distance is χ.

Table 3 Ventilation pressure for cold-formed seals

Seals

according to C-5 C-I C-3

Fig. 2 7.0+, 7.0+ 7.0+, 7.0+ 7.0+, 7.0+ 7.0+, 7.0+

Figures 3 - 2.8, 6.3 1.4, 4.2

Fig. 4 - 7.0+, 7.0+, 7.0+, 7.0+

Fig. 11 7.0+, 7.0+ 7.0, 7.0+ 2.1, 4.9

Figures 12 - 2.8, 2.4 5.4, 2.1

Figs. 13-4, 3 | ⁵ ' ^{4 2} ' ⁸ ' ⁴ ' ⁹

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Example 3

In this example, seals were made using the device cold worked according to FIG. According to Fig. 14 are Caps entered from a hopper into a transport system 21 which transfers them to an oven 22 in which they are preheated. The warm caps are passed to a turret 23 over which a tablet input device is arranged. In the Warm caps are made of the seal-forming thermoplastic tablets Material entered and passed through the conveyor 24 into a second furnace 25, in which the tablets heated to soften. The caps containing the softened tablets are placed in a rotatable forming tower 26 where the molds are inserted into the closure to deform the tablet. The forming tools are at Contact cooled either directly or indirectly with a liquid coolant. A suitable coolant is water used, which is passed through channels in the mold.

In this example "Flavorlok" caps with a diameter of 28 mm were used. They were preheated ^{to 120 °} C. in an oven 22. Tablets weighing 300 mg from compositions CI, C-3, C-4 and C-5 were introduced, the temperature of the second oven being 180 ° C. To form the seals according to FIG. 2, a corresponding molding tool was used, the surface temperature of which was about 10 ° C. during the deformation. There were no problems

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with regard to the sticking of the sealing material on the mold, although the molds were only polished and not otherwise treated. The caps produced in this way had a thickness of 230 μm in the central region, the seals exhibiting good properties in all three molded compositions. These caps were ^{applied to glass bottles with a w} Elavorlok "head. The removal torque and the venting pressure were determined; the results are summarized in Table 4. For comparison, closure caps made using the" spin-line "process with a commercially available PVC Plastisol with a seal weight of 450 mg. The sealing properties of these caps were also determined by closing a container containing three times its volume of dissolved carbon dioxide. The results are summarized in the table.

cold-formed seals according to of sealing caps 1.1 Table 4 Example 3 0.41 Unscrewing force and ventilation pressure Unscrewing force standard deviation
in kg in kg 0.23 with 5.0 0.27 component 2.4 0.50
* C-5 2.4 C-1 2.5 C-3 3.8
after this
"-Procedure) C-4 comparison
(Plastisol
¹¹ spin-line

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2 In all cases the ventilation pressure was greater than 7 kg / cm.

Table 5

Sealing property on a triple content container its volume of dissolved carbon dioxide (stored upside down and shaken for 24 hours)

C-5 1 leak in 5 containers

C-3 O """ ^H

C-40 ™ HH H

Comparison 0 "" "

(Plastisol after the
"spin-line" method)

Example 4

On a commercially available bottle filling and closing system it was found that the seals according to the invention according to Fig. 2 better with a "Flavorlpk" closure on the bottle could be brought than when using seals according to FIG. 11, which were produced in the same molding process. This result has been found for both cold and hot deformed seals.

The test of the bottles which were equipped with closure caps, which were equipped with seals according to FIG. 2, and comparative closure caps, those with seals using the "spin-line" method

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made of a commercially available plastisol showed that the seals according to FIG. 2 were lower in most cases Showed values for the unscrewing force. The results are summarized in Table 6.

Table 6 Unscrewing force (a) 4 hours after closing

Unscrewing force
in kg Standard deviation
in kg ' C-5 7.2 T, 2 C-1 4.1 0.72 C-3 4.4 0.45 C-4 4.4 O, 64 control 4.6 O, 41

(b) 24 hours after capping

From screwing force
in kg Standard deviation
in kg C-5 5.6 0.91 C-I 4.4 0.95 C-3 4.6 0.54 C-4 4.7 0.36 control 4.5 0

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An experiment was then carried out in which the container was restored were locked. A closure cap with a seal "of each composition and according to Fig. 2 opened ten times and closed again. The seal was not damaged; the sealing properties were satisfactory, when the sealed bottles have been turned upside down and shaken.

Example 5

The apparatus of FIG. 15 was designed for the hot molding of Seals used. It differs from that according to Property 14 as follows: The oven in which the caps are heated is exposed by a short, gas-heated chain that promotes the caps. This was based on an electrical sensor TZO C which was connected to a solenoid controlled gas valve. The caps were right through from 23 to 26 Transport wheels 28 promoted, which replaced the second furnace according to FIG. Both the molds and the tables were gas-heated by two separate gas rings 30 which surrounded the tower 26 at an angle of 270 °. These gas rings were controlled by two electrical sensors that controlled the solenoid operated gas valves in the same way, like the temperature control in the heating chain for the caps. It was found that the temperature control is the best was when the sensors were arranged so that they the

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Tables and the forming tools touched when the tower rotated. The system was running at 220 caps per minute
operated; a sufficiently long holding time (four seconds) was achieved at this speed.

Compositions C-1 and C-3 became gaskets according to Fig. 2 hot formed in vinyl lacquered 28 mm "Flavorlok" caps. The optimal deformation temperatures were:

Mold surface 160 ° C

Table 180 ⁰ C

When using polished stainless steel dies, there were some problems with the sealing material sticking to the die. New molds were cut from soft steel and chrome-plated. You owned a
finer and softer finish and higher thermal conductivity. The problems described above no longer occurred.

The thickness of the central area of the seals has been changed, by increasing or decreasing the compression of the mold spring. Film weight and thickness of the central Range were:

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Film weight corresponding thickness of the central area 300 mg 230 μm

240 mg 125 to

200 mg 25 µm

Example 6

Example 5 was repeated with the difference that seals according to FIGS. 5 to 10 were produced and that 28 mm RO "Coronet" aluminum caps (Metal Box Ltd.) were used. The thickness of the central area was set at 180 µm, under these conditions the film weight was increased until the narrowest areas were filled. Many hundreds of caps with this profile were made before the film weight was increased to fill the next smallest shape. To this In this way it was possible to produce good seals according to FIGS. 5 to 7 with film weights of 140, 200 and 240 mg. The seal forms 8 to 10 were not so well pronounced.

Example 7

Composition C-1 was cold formed in vinyl lacquered crown caps for taste testing. Tablets with a weight of 200 mg were placed in the middle of the crown corks and placed in an oven with circulating air ^{at 210 ° C. for two minutes.} The crown caps were then removed and placed on a hand operated toggle press

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cold deformed., with the mold at room temperature was held. (Taste tests showed that the C-1 composition had extremely good taste characteristics compared to the best plastisols currently available.)

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Claims (8)

Expectations 1. A container closure which is either threaded or can be drawn onto the container in situ, and which has a seal which, prior to application to the container has a practically flat central area and an adjoining peripheral area, characterized in that that the thickness of the peripheral area is greater than the thickness of the central area everywhere and continuous, stepped or partially continuous and partially stepped radially outwards in In the direction of the edge of the closure and that the radial distance χ between the center of the Closure and the beginning of the peripheral area 25 to 45% of the maximum inner diameter d of the closure amounts to. 2. Closure according to claim 1, characterized in that the increase in thickness is continuously radially outward in Direction towards the edge of the closure takes place. 3. Closure according to claim 1, characterized in that a step-shaped in the peripheral region of the seal Edge area is formed. 409844/0306 4. Closure according to · Claim 3 / characterized in that the edge area consists of a single step following the edge of the closure. 5. Closure according to claim 3 and 4, characterized in that that the increase in thickness takes place continuously radially outwards in the direction of the edge area. 6. Closure according to claim 2 or 5, characterized in that that the angle β between the rise of the peripheral area and the central area is from 20 to 80 °. 7. Closure according to claim 2, 5 and 6, characterized in that the increase in thickness has a constant gradient and has a planar slope from the peripheral region. 8. Closure according to claim 1, characterized in that the thickness of the peripheral area with a constant gradient increases and radially outward from the corner or limit of the central area to the edge of the closure or to the beginning of the flat part at the edge that the angle β between the rise of the peripheral area and the central region is from 25 to 50 ° that the 409844/0306 radial length of the flat part of the peripheral area
5 to 20% of the radial length of the peripheral part and that the radial length between the center of the closure and the beginning of the peripheral area is 25 to 45% of the maximum inner diameter of the closure. ugs: rew: kö 40 9 844/0306