DK145454B - Bottle closures with thread - Google Patents

Description

(19) DENMARK

| p (12) PUBLICATION ON 1451 + 54 8

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 2055/74 (51) IntCI.3 B 65 D 53/00 (22) Filing date 10 Apr. 197 ^ (24) Running Day Apr 10 1974 (41) Aim. available Oct. 13 1974 (44) presented Nov. 22; 1982 (86) International application # - (86) International filing day - (85) Continuation day - (62) Master application no -

(30) Priority 12 Apr 1973, 17646/73 * GB

(71) Applicant w.R. GRACE & CO., New York, US.

(72) Inventor John Adrian Lancaster Jemmett, GB.

(74) Associate Engineering Company Budde, Schou & Co.

(54) Bottle cap with thread.

The invention relates to a bottle closure of the kind specified in the preamble of claim 1.

To enable the customer to close the bottle again after it has been opened, it is desirable to provide a threaded closure which can be removed by unscrewing. A common type of thread closure which has gained wide commercial recognition is the type whose thread is formed while the closure is placed in the closure position of the container: A closure which, initially D with no thread, has been placed on a bottleneck with thread and ^ pressure is exerted against the closure so as to form threads herein, corresponding to the threads formed on the bottleneck. The thread on the closure may e.g. formed by means of a rolling means. It has been used.

- various types of sealed threads or caps, which include closures of the kind known from the specifications of British Patent Nos. 975,739 and 1,054,295.

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The gaskets for which the thread is formed on the bottle have so far been often manufactured by measuring a predetermined amount of a polyvinyl chloride plastisol in a closure, which is then rapidly rotated about an axis extending through the center of its cover plate, the plastisol is distributed by the centrifugal force, after which the plastisol placed in the closed is liquefied. The plastisol is a viscous dispersion of polyvinyl chloride in a plasticizer. It is liquefied by heating to a temperature at which the plasticizer is taken up in the polyvinyl chloride to form a homogeneous mass which, upon cooling, becomes a rubber-like solid.

This process - although it has been a commercial success - has some limitations. One such limitation is that the shape of the gasket cannot be changed much. Because the gasket is formed under the influence of centrifugal force, it is inevitable that the thickness of the gaskets produced will increase gradually from the midpoint of the center portion to its circumference. Since it is generally advantageous to be able to use gaskets of different shapes for different types of container closures or containers, it is a serious limitation of the process that it cannot be used in the manufacture of gaskets of other designs. Another problem with the process is that in the manufacture of large series of closures or capsules, it is difficult to insert the packing material in a symmetrical manner in the central area of the closure, so that when the closure is rotated quickly, the sealing member will not be fully formed in the desired shape.

SUMMARY OF THE INVENTION It is an object of the invention to provide a new design of a bottle closure of the kind specified in the preamble of claim 1, wherein the above-mentioned problems have been remedied or avoided.

It should be emphasized here that the invention relates only to closures of the kind having a skirt intended to be deformed against the glass surface of the bottle to form threads that allow a user to unscrew and screw closed. This kind of bottle closure thus differs substantially from the kind of crown closure known e.g. U.S. Patent Nos. 2,543,774 and 3,339,774, wherein the seals comprise center portions and circumferential portions, the latter of which are designed and arranged to provide a sufficient seal on the bottleneck end surface.

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GB Patent No. 975,739 discloses that the placement of gasket material in the corner between the skirt and the cover plate on a closure of the kind provided with the in situ may improve the sealing effect, so that a sufficient amount of plastic material is placed in said corner by a process of the above-mentioned type, causing the packing material to extend from a location on the skirt spaced from the cover plate over the center of the cover plate to a corresponding location on the opposite side of the closure with a meniscus-shaped portion with a curved surface therebetween two diametrically opposite locations at the perimeter.

Such a device and design is disadvantaged by the fact that the surface of the meniscus is not necessarily rotationally symmetrical due to the centrifugal scattering process used to project the plastisol into the corners of the closure.

Furthermore, it is very difficult to precisely place the plastisol on the axis of rotation, and an eccentric placement can cause an uneven distribution of the packing material.

In order to ensure a sufficient sealing function at all points around the opening of the bottleneck, it is necessary, in the application of the process, to ensure that a certain minimum quantity of plastic material is present in the closed, so that at all points there will be a certain, indispensable minimum of plastic material.

However, excess packing material at some diameters will in itself be an obstacle to the closure being properly sealed to the bottle and will further incur additional costs in the form of the cost of the excess material.

The sealing compositions known from U.S. Patent Nos. 2,543,774 and 3,339,774 are formed to provide the requisite annular circumferential portion close to the closure skirt to form the desired seal at the top of the bottleneck, but have no circumferential portion. extending down the side of the top of the bottleneck. Although the design described in these writings will be acceptable for a crown closure based on sealing against the upper surface by means of a thin gasket, a closure provided with an in situ thread and in which such gasket will be used not have any seal to the side.

US Patent No. 3,411.649 discloses a tab cap, i.e. a cap which, at the free edge of the skirt, has a tab for engaging 4 U5454 a tab on the glass surface of the bottle. In such tab caps only an annular gasket is required and no middle portion. Although the cap disclosed in this patent has a central portion, it is only intended to serve as a heat barrier in pasteurization and consists of vinyl-plastisol foam formed by insertion of a shaped disc or by a process thereof. the above-mentioned species. Thus, the resulting combination of a ring gasket and a heat barrier does not constitute a one-piece liner or gasket, and the center portion does not contribute to the sealing function.

The above object is achieved by a closure formed according to the invention as defined in the characterizing part of claim 1.

Thus, the invention provides a gasket having the required amount of sealing material in the corner between the skirt and the cover plate, but having well-defined boundaries of the radial extent of the center portion and a well-defined contour of the circumferential portion. The advantage of this perimeter portion, whose thickness increases continuously and / or incrementally radially outward, is that the sharp transition between the center portion and the perimeter portion can be accurately placed and kept precisely symmetrical with respect to the cap or cap cover plate center, and further, the profile of the perimeter portion can be varied. within wide limits, under the general restriction, the thickness must increase externally, in order to achieve the optimum design of the contact area of the gasket with the edge of the bottle neck to ensure an effective top seal and side seal using a minimum amount of plastic material, and under certain assurance that the gasket mass has the same profile for all diameters, so that the gasket will be eccentric and that more material is used than is necessary.

In the embodiment of claim 2, special advantages are obtained from the use of the closure on bottles with certain types of glass surfaces.

In the embodiment according to claim 3, the seal occurs more on the upper edge of the bottle neck than on its sides, compared to the embodiment according to claim 2, and here also special advantages are obtained in connection with certain types of glass surfaces.

At the value specified in claim 4, the acute angle between the inclined surface of the circumferential portion and the middle portion achieves the right balance between sealing on the top of the bottle neck and on its sides to obtain the best result.

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BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in more detail with reference to the exemplary embodiments shown in the drawing. 1 in diametrical cross section shows a down gasket equipped according to the invention, as well as a molding die which can be used in forming the gasket; FIG. 2-7 in diametrical cross-sectional views illustrate seals equipped with gaskets according to the invention; 8-10 in diametrical cross sections show seals equipped with gaskets according to the invention, in which the gaskets are designed in a different way than shown in FIG. 2-7, FIG. 11 and 12 schematically show apparatus for forming the gaskets; 13 and 14 are cross-sectional bottle caps of the type "Coronet" and "Flavorlok" respectively. 15 in diametrical cross section shows a closure equipped with a different configuration than the invention.

In FIG. 3-10 and 15 are (for space purposes) shown only those parts of the bottle cap containing the gasket. The shutter height is the same as shown in FIG. 2nd

FIG. 1 shows a bottle cap facing up / down before being attached to a bottle to close it. The capsule consists of a cover plate 1 and a skirt 2, of which only a portion is shown. A gasket 3 comprises a generally planar middle portion 4 and a circumferential portion 5 with an upwardly extending outwardly inclined surface 6. The inclined surface 6 is shown to be tapered, i.e. the rectangle in cross section, but it could also be designed with concave or convex curvature. The radial distance between the center of the capsule and the beginning of the elevated circumference portion 5 of the package is indicated by x, and the angle between the bevel surface 6 and the planar middle portion 4 by 3. The dashed lines in the drawing are geometric guides. FIG. 1 also shows a portion of a mold die 7 whose forming surface comprises a flat center surface 8, the size of which corresponds to the size of the middle portion 4 of the package, and a circumferential bevel 9, the inclination and dimensions of which correspond to the shape of the package's peripheral part 5. The corner area 10 of the package The corresponding corner area 11 on the forming surface of the molding mold 7 is preferably slightly rounded to achieve a more gradual profile transition between the middle part 4 and the circumferential part 5.

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The angle β can be between 20 and 80 °. These values for the angle β apply to such gaskets in which the circumferential portion has a constant angle of inclination from the edge of the skirt to the skirt, and for those gaskets in which the circumferential portion consists of a single step and has a constant inclination angle from the edge of the skirt to where the plane portion of the step begins. . It is preferred that the width of the planar portion is from 0.1 to 50% of the radial extent of the circumferential portion, preferably from 5 to 20%.

The radius x is between 0.25d and 0.45d, where d is the largest inner diameter of the capsule. Good sealing properties have been achieved with "Flavorlok" capsules in which the radius x of the gaskets is between 0.37d and 0.42d. One type of gaskets according to the invention, which are particularly preferred, are those in which the thickness increases, under one. constant angle of inclination from the edge of the middle portion to the skirt of the capsule or to the beginning of a flat portion or plateau portion to the skirt where β is between 20 and 80 °, preferably between 25 and 50 °, x is between 0.25d and 0.45d, preferably between 0.37d and 0.42d, and wherein any planar portion or plateau portion of the skirt has a radial extent of between 0.1 and 50%, preferably between 5 and 20%, of the radial extent of the circumferential portion.

In general, the mold cartridge will be slightly smaller than the inside diameter of the capsule, so that the molding during molding can enter the capsule with clearance. Thus, there will be an edge portion on the package corresponding to the clearance between the molding and the closure skirt. In the discussion and in the definition of the seals according to the invention, this edge part is disregarded; i.e. that the periphery of the package is considered synonymous with the molding die used in the manufacture of the package and with closed skirt. FIG. 2-10 shows caps or closure caps with inserted gaskets. FIG. 2-4 show designs of the packages for a "Flavorlok" capsule having an internal diameter of 2.67 cm, while FIG.

Figures 5-10 show designs of packages for a "Coronet" capsule, whose largest internal diameter is also 2.67 cm. The 2-7 gaskets are of the inclined surface type, the values of β and x being as follows:

U5A5A

7

FIG. 2 3 4 5 6 7

Angle β (°) 30 30 45 30 30 45

Radius χ 0.40d 0.37d 0.38d, 0.385d 0.37d 0.37d

The 8-10 packages have values for x of 0.34d, 0.31d and 0.33d, respectively.

The Corners P and R shown in Figures 2-4 and 8-10 may be sharp or rounded. In FIG. 2-4 is the radius of curvature at P - i.e. at the beginning of the circumference - 0.25 mm. In FIG. 8 and 9, the radii of curvature at P and R are 0.25 and 0.51 mm. 10, it is 0.51 mm at P and R. The degree of curvature at these locations can be changed within wide limits.

The height h of those in FIG. The circumferential portions of the packings shown in Figure 8-10 can be varied according to the type of capsule and bottle used. In FIG. 8-10 this height is approx. 1.0 mm.

FIG. 8-10 illustrate another preferred embodiment of the invention, namely packings whose circumferential portion consists of a single stage with a planar portion or plateau portion whose radial width is between 65 and 98% of the total radial width of the circumferential portion.

Two major types of molding processes have been found to be suitable for preparing the gaskets of the invention. The first type is referred to as "cold forming". A solid blank of gasket-forming material, e.g. a pill as described above is placed in an up and down bottle cap which has preferably been preheated to support the subject's attachment to the closure. Thereafter, the closure is heated to a temperature above the softening temperature of the packing material, e.g. on a press counter or in an oven, and the gasket is formed by means of a molding die, the surface of which is cooled below the softening temperature of the gasket-forming material by continuous or discontinued cooling with a coolant. Preferably, the forming surface of the molding mold is kept at a temperature below 100 ° C. A temperature between 5 and 25 ° C, in particular approx. 10 ° C, has been found to be very suitable for polyvinyl chloride. If desired, the closure during the molding can be heated by means of the press retainer.

The second type of molding process is hot molding, which differs from the former in that the molding mold is neither actively cooled by a coolant nor heated. Also in this process it is preferred that the restraint is heated. This second type of molding process is not the most suitable for certain packing materials, e.g. mixtures of polyethylene and butyl rubber, but it has been found that it can be used to form plasticized polyvinyl chloride. Solid, plasticized polyvinyl chloride is a material that has already been gelled, and as soon as this has occurred, the material behaves like a regular thermoplastic resin. It can withstand heating to the softening point. Good results have been obtained with gaskets which have been formed at approx. 160 ° C. In general, temperatures in the range of between 150 and 170 ° C are likely to be suitable for both the molding and the resist. At these temperatures, the residence time, i.e. the time period during which the mold cartridge contacts the gasket material is usually relatively long, e.g. from 3 to 6 seconds, depending on the temperature. A long residence time is desirable for softening the upper and lower portions of the polyvinyl chloride pellet upon prolonged contact with the relatively hot mold.

The pressure exerted by the molding mold during the hot molding,

ISLAND

can be relatively low, e.g. 28 kg / cm. Generally, it will not be less than 4.9 kg / cm or greater than 140 kg / cm.

For bottle closures or capsules equipped with gaskets according to the invention, plasticized polyvinyl chloride is preferably used, since this material is well recognized as satisfactory for use in gaskets. The plasticized polyvinyl chloride is conveniently introduced into the capsule or closed in the form of a pill, the diameter of which is usually smaller than that of the closure. The use of solid, plasticized polyvinyl chloride has several advantages over the use of a plastisol. One of the advantages is that suspension-quality PVC resin can be used, unlike the emulsion-grade PVC resin, which is usually used in plastic insoles. The suspension-quality resin contains no emulsifier. - Some emulsifiers affect polyvinyl chloride in such a way that a gasket made from it can give the bottle's beverage content an unpleasant taste. It is therefore an advantage that suspension-quality resins can be used. Another advantage is that the pills of polyvinyl chloride can be placed exactly in the middle of the upside-down capsule, so that a more accurate placement of the gasket is achieved than in the above process. A further advantage consists in the fact that the solid pellets can be easily prepared by cutting an extruded rod. Rod material is easier to handle than plastic insoles. While the plastisols are required to have a certain viscosity which must neither be too high nor too low, there are no such limitations in the use of rod material, and so the choice of packing material is freer.

The plasticized polyvinyl chloride may, of course, contain one or more of the usual additives, e.g. stabilizer, filler, pigment, lubricant and lubricant. The properties of the plasticizer are not critical. Thus, di-isooctyl phthalate or any of the other usual plasticizers can be used.

In the manufacture of the gaskets according to the invention, it is also possible to use several different gasket materials in addition to PVC. Mixtures of polyethylene and butyl rubber having a content of e.g. 40-70% by weight polyethylene and 60-30% by weight butyl rubber are generally suitable for the purpose. The mixtures are preferably formed by cold forming.

Gaskets with those of FIG. 2-4 yeast designs have been found to be particularly suitable for closure using a "Flavorlok" closure head. In such a closure head, while being held axially in abutment against the bottleneck end, is reformed by being squeezed radially inward at the corner where the skirt is connected to the cover plate. A closure head of this type is disclosed in the specification of British Patent No. 975,739.

Using the embodiment of FIG. 11, the capsules are fed from a capsule hopper to a conveyor 21 which leads them to an oven 22 in which they are preheated. The hot capsules are passed on to a carousel 23, over which a pellet loading mechanism is provided. Pellets of gasket-forming thermoplastic material are loaded into the hot capsules which are then passed by a conveyor 24 to another furnace 25 in which the pellets are heated to soften them. The capsules with the softened pellets placed therein are passed to a molding carousel 26, where mold cartridges are inserted into the capsules to form the pill. The mold cartridges are cooled by indirect or direct contact with a coolant. Suitably, the coolant may be constituted by water flowing through channels in the mold.

The FIG. 12 differs from that of FIG. 11 is shown as follows: The capsule preheater is replaced by a short loop 27 of a gas-heated capsule conveyor chain which is held at 120 ° C by means of an electromagnet controlled gas valve and an associated electric temperature sensor. The capsules are directly transferred 145454 xo from the feed carousel 23 to the rotary molding carousel 26 by means of transfer wheel 28 which replaces the one shown in FIG. 11. Both the mold cartridges and restraints are gas heated by two separate gas rings 30 surrounding the carousel 26 at an angle of 270 ° C. In this process, the apparatus operated at a rate of 220 capsules per minute, allowing this time to be sufficiently long, namely 4 seconds.

The invention will now be illustrated by the following examples. The following mixtures C-1 to C-5, based on suspension grade PVC resin, were extruded in the form of an 8 mm diameter rod.

Mixtures (by weight)

Ingredients C-1 C-2 C-3 C-4 C-5 PVC resin '- 100 100 100 100 100

Di-isooctyl phthalate (plasticizer) 55 55 55 ° 0 ° 5

Low molecular weight polyethylene (Lubricant A) 0.5

Paraffin Wax (Lubricant B) - 0.75 0.75 "Vaseline" (Lubricant C) - 0.75 0.75

Stabilizer · -. 5 5 5 5 3

All numbers denote female parts.

Example 1

Pills of mixtures C-1 to C-4 weighing 330 mg were cut from rod material and placed in the middle of "Flavorlok" capsules of type 28 mm aluminum RO. The pellets were then hot-formed in a hot-forming apparatus to form gaskets of the one shown in FIG. 2. The equipment used for this included a mold die and an electric heating resistor, which could be individually regulated to any temperature up to 250 ° C.

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The applied power was at most approx. 150 kg, corresponding to a pressure of approx. 25 kg / cm. The conditions were as follows:

The mold die temperature is 160 ° C

Counter temperature 210 ° C

Duration 6 sec.

After less than 4 hours of molding, these capsules were placed in a closed position against dry glass (with surface properties similar to MCA 1) and measurements of the torque needed for the unscrewing were made immediately after the closing operation. The results are shown in Table 1.

Table 1

Screw torque against dry glass (gasket according to Fig. 2)

Mixture Average Screw Torque (cm / kg) C-1 15.9 C-2 17.9 C-3 5.4 C-4 5.2

Example 2

Mixtures C-1, C-3, C-4 and C-5 were hot-formed under the above conditions and using a capsule of the same type. From each of the four mixtures, three seals with inclined circumferential portion (Figs. 2, 3 and 4) and three seals with annular ribs (Figs. 11, 12 and 13) were prepared, and with the following values of membrane weight: Figs. 2 330 mg fig. 3 410 mg fig. 4 370 mg

These weight values were measured by weighing the pills. Pills with these weight values completely fill the "mold space" between the mold cartridge and the capsule, forming seals in which, for all six designs, the middle portion has a thickness of 0.23 mm. These capsules were allowed to "age" for 24 hours before being placed in a closed position against dry glass. The screw-off moments were then measured and the results (Table 2) showed that C-1 and C-3 gave the lowest screw-off moments.

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14545A

Table 2

Screw torque against dry glass for hot-formed gaskets

Average Screw Torque Scattering

Mixture_Gasket according to_ (cm / kg) _ (cm / kg) C-5 fig. 2 21.9 4.2 C-1 FIG. 2 6.1 0.58 03 FIG. 2 8.3 0.92 04 fig. 2 7.8 1.2

The ability of these capsules to provide a tight closure of a pressurized bottle was determined by measuring the "leakage pressure", which is the pressure at which the closed capsule permits leakage of the gas content of the bottle and is usually measured by blowing nitrogen through a hole in the bottom of an encapsulated bottle which is submerged under water. The nitrogen pressure is increased until bubbles emerge from the underside of the capsule, and the pressure at which this occurs is calculated as the leakage pressure of the capsule under test.

Capsules with inserts of mixtures 05, O1, 03 and 04, which were formed by molding, were placed in a closed position on glass bottles with MCA 1 surface using a "Flavorlok" closure head. The leakage pressure of these capsules was then measured (see Table 3). The results showed that only the capsules whose seals were shaped as shown in FIG. 2 and 4, could withstand pressures above 7 kg / cm2. The 3 showed poorer results than those in FIG. 2 and 4. It is conceivable that the reason for this is found in a difference with respect to the place where the sealing pressure is greatest, which is probably a function of the radius x.

Table 3 2

Leakage pressure for cold-formed gaskets (kg / cm)

Gasket according to_C-5_C-1_C-3 FIG. 2 7.0+; 7.0+ 7.0+; 7.0+ 7.0+; 7.0+ 7.0+; 7.0+ FIG. 3 - 2.8; 6.3 1/4; 4.2 fig. 4 - 7.0+; 7.0+ 7.0+; 7.0+ ("7.0+" means "more than 7.0")

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Example 3 In this example, the gaskets were cold-formed using the one shown in FIG. 11.

The capsules used in this experiment were "Flavor-loc" capsules with a diameter of 28 mm. They were preheated in the oven 22 to 120 ° C. Then pills weighing 300 mg of mixtures C-1, C-3, C-4 and C-5 were loaded and the temperature of the second oven was 180 ° C. A mold die was used to form gaskets of the one shown in FIG. 2, and during molding, the surface temperature of the mold cartridge was approx. 10 ° C. No problems occurred with adhesive of the packing material to the mold, although this was only polished and had not been subjected to any special adhesive preventive treatment. In capsules thus prepared, the thickness of the center portion was 0.23 ram, and the packages exhibited good quality with all the blends used for the molding. All of these capsules were placed in the closure position on glass bottles using a "Flayorlok" closure head. The results for the torque and leakage pressure are shown in Table 4. Capsules prepared according to the previously mentioned method and with gaskets formed from a commercial PVC plastisol with a weight of 450 mg were used for comparison. The capability of these capsules for close closure was also assessed by placing the capsules in the sealing position on bottles in which the contents dissolved in 3 volumes of carbon dioxide. The results are shown in Table 5.

Table 4

Screw torque and leakage pressure for capsules with cold-shaped gaskets according to Example 3_______

Average Unscrew- Scattering

Mixing torque (cm / kg) - (cm / kg) - C-5 12.7 2.9 C-6.2 6.2 C-3 6.0 0.58 C-6.5 6.5 0.69

Comparison capsule with plastisol g 7 - 3 In all cases the leakage pressure was greater than 7.0 kg / cm

Table 5 Sealing Capacity of 3-Volume Dissolved CO 2 Containers (Stored with Neck Down for 24 Hours and then Shaken) C-5 1 Leak Container of 5 Tested C — 1 0 11 ”11 11” C — 3 0 11 11 11 11 11 q_ 4 0 11 11 11 11 11

Comparison capsule with plastisol 0 "" "" "

When attempting to fill bottles in a commercial bottle filling plant, it was found that gaskets according to the invention with the one shown in FIG. 2 could be placed more evenly in the closing position by using a "Flavorlok" closure head than gaskets having the one shown in FIG. 15, which was made by the same molding process. This result was obtained in both hot and cold-formed gaskets.

A repeat closure test was performed. A capsule with one gasket made of each mixture formed as shown in FIG. 2, was opened and closed again 10 times. No damage was seen to the package, and the ability to close tightly was satisfactory when flasks closed with these capsules were flipped upside down and shaken.

Satisfactory experiments were also performed using 28 mm RO "Coronet" aluminum capsules.