DE1176014B - Process for the production of a sealing insert made of elastic foam plastic in crown closure caps - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: B 67 b

Number:
File number:
Registration date:
Display day:

German class: 64 a -43/01

1176 014
C 17955 III / 64 a
November 28, 1956
August 13, 1964

Crown locks with an elastic sealing insert made of foam plastic are known per se. The known Sealing inserts of this type are either separated from the closure cap in separate Forms or made in the closure cap, whereby a plastic enriched with gas, which is not stable under atmospheric conditions, using overpressure or underpressure and heat is applied to the shape of the sealing liner. These known procedures require a relatively complicated and expensive facility for making the gas-filled plastic and for foaming and solidification of the sealing inserts, and the manufacturing process is cumbersome and is time consuming.

The object of the invention is to provide a simple device and little in terms of the required devices elaborate procedure to specify, with the help of which crown locks with elastic, made of foam plastic existing insert can be produced, the quality of which is in no way behind that of the known crown locks.

To solve this problem it is proposed according to the invention that in per se known Put directly into the cap a compound composed of vinyl chloride resin and a plasticizer Mass is introduced, which forms a plastisol and at atmospheric pressure with an inert gas was saturated and that in this saturated state under atmospheric pressure can be stored, whereupon the paste-like mass located in the cap with simultaneous Application of heat is exposed to a pressing pressure and shaped, it foams and at the same time in the resulting cell structure is made resistant.

A major advantage of the invention is that the plastisol forming with an inert gas saturated mixture for a longer period in an open vessel, d. H. so at atmospheric Pressure, can be kept in stock without the mixed-in inert gas escaping from the mixture. In contrast to the known methods, it is therefore not necessary to first go directly into the plastic compound to mix in the gas before processing them into crown capsule inserts, or else the gas that has been produced in advance Store foam mass in appropriate pressurized or negative pressure containers. In addition, the actual production of the insert having the cell structure is extremely simple and apart from a heatable ram, practically no special devices are required.

Process for the production of a sealing insert made of elastic foam plastic in crown caps,

Applicant:

Crown Cork & Seal Comp. , 'Inc.,

Baltimore, Md. (V. St. A.) ■ "

Representative:

Dipl.-Phys. W. Kemp, patent attorney,
Cologne-Lindenthal, Goldenfelsstr. 24

Named as inventor:

John W. Normandy,

Washington, D. C. (V. St. A.)

Claimed priority:

V. St. v. America November 29, 1955
(549 831)

In a further embodiment of the invention, the method is characterized in that the cap, the is provided inside with a lacquer coating in a manner known per se, not significantly higher than Room temperature is heated, while the forming punch exerting the pressure is heated and thus provides the heat required for foaming and solidification. The arrangement of a Lacquer coating on the inside of the crown connections is known per se. With the known methods, in which the foam insert is made in the cap, it is necessary that To heat the cap while the foam solidifies. Most of the time it burns the inner lacquer coating of the cap, or it is decomposed by the plastic material of the insert. In contrast, the invention has the advantage that the closure cap in the manufacture of Foam insert not significantly over space

temperature is heated and thus the inner lacquer coating cannot be damaged under any circumstances.

The inventive concept of the invention is of course not limited to the production of Crown locks with elastic, foam plastic sealing insert, but in an analogous manner also includes the production of screw closures with elastic sealing elements

409 640/49

location and the manufacture of other closures with an elastic insert.

Further details of the invention emerge from the description, with reference to the drawings Is referred to. It shows

F i g. 1 is a section through a container in which the vinyl chloride resin plastisol is carried with the gas added and the finished mixture is kept in stock,

F i g. Figure 2 is a top view of one with the opening upwardly lying crown cap, which is provided with one of the improved foam linings is,

F i g. 3 shows a section through the in FIG. 2 cap shown,

4 shows a section through the cap on an enlarged scale Scale and

F i g. 5 a stepped tool, which can be used as a ram in the method according to the invention.

In the drawings, reference numeral 2 denotes an open vessel in which vinyl chloride plastisol 4 is included. Carbon dioxide gas, which is indicated by gas bubbles 6, is at atmospheric Pressure and atmospheric temperature from a cylinder filled with compressed carbon dioxide introduced through a reducing valve (not shown) and a pipe 8 into the plastisol.

In the F i g. 2 to 5, the reference number 10 denotes a crown cap made of metal, e.g. B. tin-plated Steel, which has a corrugated edge 12 and on all sides with a coating 14 made of vinyl resin varnish is provided. Such a paint consists, for example, of a mixture of 80% of a vinyl chloride Vinyl acetate copolymer (87% vinyl chloride) and 20% of an oleoresin converter, especially Wood oil-phenyl-phenol-formaldehyde resin in one organic solvents such as 70% xylene and 30% isophorome. On the varnish coating is a liner 16 made of foamed vinyl chloride plastisol is molded so that it has a middle Forms recess 18 which has a thicker edge 20 at a distance from the wall of the cap.

F i g. Figure 5 shows a stepped tool or ram 22 that is being used during treatment a cap 10 can be used, in the middle of which a pile of vinyl chloride plastisol 24 was applied. The stamp can e.g. B. by electrical heating elements 26 or by any other conventional heating device can be heated.

The punch used as a pressing tool is known per se in the manufacture of crown capsules. He is provided with a medium elevation and works so that a larger proportion of plastic material is arranged in the form of a bead near the edge of the crown cap, this bead cooperates with the edge of the bottle mouth to ensure that the bottle is properly sealed. The sealing insert is relatively thin in the middle, which saves plastic material. Of course the use of a ram without gradation is within the scope of the invention.

The pressing pressure is not particularly critical and generally only needs to be large enough to give the insert the desired shape. It is important that the pressure is not too great, because at high pressures the possibility of developing a uniformly usable cell structure is impaired and the gas is squeezed out. A compression pressure of 0.007 kg / cm ² has given satisfactory results, and such a low pressure is preferred for ease of working and to avoid excessive compression. Since, with the exception of a few exceptional cases, satisfactory economic results are achieved at very low pressures, the use of higher compression pressures offers no advantage.

ίο The ram has a temperature between 150 to 200 ° C, preferably from 170 ° C.

The crown cap does not need to be heated, so it can be at room temperature.
The treatment time is usually a few, about 1 to 10 seconds and depends on the particular heating device used. The gas used to saturate the plastisol is preferably carbon dioxide. However, other inert gases such as air or nitrogen oxide can also be used.

While the plastisol is preferably fully saturated with the carrying gas to the maximum to maintain foaming when molding the gasket; however, it is also possible to use less gas with a correspondingly reduced foaming. So z. B. an amount of gas be used, which is sufficient to produce an at least 10% saturated solution at atmospheric To give pressure and room temperature.

A higher degree of saturation is of course preferable.

The ratio of plasticizer to resin can

vary in the plastisol in a conventional manner, e.g., 50 to 150 parts plasticizer to 100 parts Resin.

example 1

100 parts of finely comminuted polyvinyl chloride are mixed at 66 ^ä / s parts of di-2-ethylhexyl phthalate, and 3 parts of calcium stearate in a (Easter) mixer for about 1 minute at room temperature. The resulting composition is saturated with carbon dioxide at room temperature and atmospheric pressure by passing the carbon dioxide through the plastisol mixture from a delivery point as indicated above in connection with the apparatus. This mixture can be left to stand in an open vessel for at least 4 days without any noticeable loss of carbon dioxide. Furthermore, there is no degassing, ie no escape of carbon dioxide from the plastisol, until it is heated.

0.35 grams of said carbon dioxide-saturated vinyl chloride plastisol is placed as a pile in the center of a conventional crown cap which has a coating of conventional vinyl chloride-vinyl acetate lacquer, as explained above. Then the stepped stamp, which has a temperature of 170 ° C, is brought to act on the cap with a pressure of 0.007 kg / cm ² (the weight of the stamp), which causes the plastisol to expand and to foam, so that the Deposit is formed. The stamp is left to act on the soft mass for 7 seconds in order to finish it and then lifted off. The cells formed in the foam-made insert are self-contained. Crown closures with foam inserts according to this example were used to close bottles with pressurized

Drinks, such as cola drinks, soda water, beer, tested and resulted in a satisfactory in each case Seal.

Example 2

Example 1 is repeated, but instead of the plastisol saturated with carbon dioxide shortly after it To use preparation, the composition is allowed to stand overnight to equilibrium conditions to reach. When equilibrium has been established in this way, it will with Carbon dioxide-saturated plastisol is placed in a crown cap and the insert is shaped as in the example. The inserts formed according to Example 2 were those according to Example 1 in this respect superior than they were more uniform in their porosity and an average finer Pore structure and therefore had a better appearance.

Claims (3)

Patent claims: 1. Process for the production of an elastic sealing insert made of foam plastic in crown caps, characterized in that in a known manner directly into the cap of vinyl chloride resin and a plasticizer compound is introduced, the forms a plastisol and has been saturated with a carry gas at atmospheric pressure and which can be stored in this saturated state under atmospheric pressure, whereupon the paste-like mass located in the cap with simultaneous application of Heat is exposed to a pressure and formed, it foams and at the same time in the emerging Cell structure is made resistant. 2. The method according to claim 1, characterized in that the cap, which is known per se Way is provided with a lacquer coating on the inside, not much higher than room temperature is heated, while the shaping stamp exerting the pressure is heated and so is used for making up and solidifying supplies the required heat. 3. The method according to claim 1 and 2, characterized in that for producing a foam insert with closed cells the form-giving ram for 7 seconds and at a temperature of 170 ° C is pressed. Considered publications:
U.S. Patent Nos. 2,389,761, 2,427,699, 2,663,909; Swiss patents No. 277 087, 295 319. 1 sheet of drawings 409 640/49 8.64 © Bundesdruckerei Berlin