DE1245107B - Method and raw material for producing a seal from rubber or similar materials on a container closure - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY B 29h

GERMAN

PATENT OFFICE Int Cl ..

German class 39 a6 - 7/20

CO 9 K 3/10

EDITORIAL

number
File number·
Filing date
Display day

1245 ίΟ7
G314iJ5 X / 39 a6 January 20, 1961

20th of July!

1967

The invention relates to the manufacture of seals for container closures, i.e. sealing inserts for metal or plastic caps, ζ Β so-called Crown caps, with which glass containers or bottles α are closed

For the production of sealing inserts for container closures In the usual processes, aqueous dispersions of rubber-like raw materials are used applied and then dried. Such seals generally have good sealing properties, but the application is relatively difficult and very tedious; Furthermore the sealing inserts produced in this way are uneven and therefore only serve their purpose incompletely

The raw material is generally produced from a nozzle injected into the rotating container closures. This causes fluctuations both in width as well as the thickness of the seals, especially at the point where the applied or sprayed on Strip of sealant overlapped. The difference in thickness between this point and the remaining areas of the deposit can be up to 25% This leads to leaks or even to a complete failure of the sealing insert, especially when the closure has to be vacuum-tight

For the production of usable sealing inserts by this method are also very Long drying times are required, the drying time is often 60 to 90 minutes Eme faster Drying is not possible because otherwise the vaporous water escaping will tear open the surface of the seals, resulting in a Coarsely open cell structure leads to long Drying times move those contained in the mass Protective fabrics and stabilizers to the contact surface of sealing insert with sealing cap, which considerably worsens the adhesion will

It is also already known to use em with a soluble Polyvinyl chloride plastisol saturated with natural gas To apply container closures and the mass under the simultaneous action of heat and In this way, a foamed seal is made with light pressure to foam and deform closed cell structure obtained The process is carried out so that a heated stamp is on the mass injected into the container closure is printed The stamp must remain in contact with the mass until the dissolved gas passes through the Heating in the form of fine gas bubbles. Procedure and raw dimensions for producing a Seal made of rubber or similar materials on a container closure

Applicant;

W R Grace & Co, Cambridge, Mass (V St A)

Representative ,

Dr rer nat J D Frhr ν Üexkull,

Patent ^attorney;

Hamburg-Hochkamp, Kojmggratzstr. 8th

j

Named as inventor 1

Allen B Foye, West Bridiewater, Mass

(VStA) 1

Claimed priority i

V St ν America from 5 February 1960 (6878) -

and the mass is polymerized
individual closures under d
wise slow and therefore fui
production at the highest possible
not satisfying

The invention is therefore
reasons, seals with ob
permanent sealing property

and is also dei like to linger ; m stamp compare its modern mass working speed

; to free yourself from the task, always equal to one as possible

; llen, which one possible The invention

simple procedure
high output per unit of time
dung accordingly relates to a Ve -Head for establishing a seal of rubber sr od analogous materials in EMEM Behalteryerschluß, gleichriaßig prevailed at the eme the Behalterverschluß with gas dispersion Rohm

under warming and pressure too

isse applied and a solid seal

is deformed According to the invention it is proposed that that the Druckverfon Dung mi the warming at the at the Verschuf dry, spongy seal open pong structure under em 5m for Crushing the cavities in the calibration is taken

This achieves that, in contrast to the known Method using chewing

709 617/218

chuk dispersions or similar masses the Drying can take place very quickly, as the resulting open cell structure is then eliminated The deformation of the cooled spongy sealing insert can be carried out extremely quickly, since only a single, stronger pressure is required. The one associated with heating the stamp There is no appaiative effort the spongy structure is only successful with the raw materials made of rubber or equivalent Materials, while ζ B plastisols after cooling are no longer deformable. Due to the deformation, all of the Mass m the container closures occurring irregularities or differences in thickness are completely eliminated

The invention also relates to the raw material Rubber latex or similar materials for carrying out the method It is according to the invention characterized in that the rubber latex is em natural rubber latex, the one with a finely divided Aqueous dispersion containing fillers and ammoniacal soap is mixed

The invention is to emes in the following with hand Example will be explained in more detail, in which all quantities are given in weight points

example

Em mixture of 50 parts of oleic acid, 50 parts of paraffin oil, 150 parts of water and 20 parts of a 28% ammonia solution becomes intimate with each other mixed Then 15 parts of iron oxide and 2000 parts of barite are slowly added to the mixture and until the fillers are fully dispersed Then 600 parts of a 60% concentrated natural rubber latex and then are stirred 300 parts of talc for the fuel dispersion added The mass is stirred until until it is supple and smooth, whereupon eme 40% bentonite solution and 5% karaya gum solution be added to give the mass the necessary rheological properties

The sealing compound produced in this way contains considerable amounts Amount of air in the form of very distant bubbles dispersed in the mass The amount of air is about 20 percent by volume of the mass and is so stably dispersed in it that the Mass can be stored for several months without significant air loss

To prevent premature hardening of the mass, em harder is prepared and the mass added immediately before use The hardener consists of 3 parts of sulfur, 3 parts of zinc dibutylditmocarbamate, 10 parts of Zmkoxyd and 16 parts of water, which mmg in a ball mill The hardener is m the sealant stirred in, whereupon this is applied to several metal container closures by means of a nozzle

The closures or lids are about 1 minute placed in an oven with a temperature of 193 ° C for a long time, then removed and cooled to room temperature The sealant is completely dry and has turned in eme heavily bloated mass with small, evenly distributed and interconnected air cells. This cellular mass has a completely open structure, that is, the surface of the sealant forms a dense film, rather than a core is interrupted by a multitude of tiny openings, which with the cells in the sealing insert related

The cellular mass therefore still represents a useful seal because it is too soft and spongy and, when used as a sealing insert, results in poorly sealed containers. cm ² exerted The open cell structure is compressed by the pressure and the sealing layers obtained are smooth, compact, of extremely uniform thickness and show excellent adhesion to the closures or lids. In particular, after the pressure treatment, the sealing inserts have uneven areas at the points where the liquid mass overlaps after application

The sealing layers obtained in this way have precise dimensions and show excellent sealing properties

The presence of a sufficient amount of air in the liquid mass is necessary for the implementation of the The process is essential because it creates a sponge-like, easily compressible sealant layer which is formed under pressure to its final Large size and shape can be condensed It is also necessary that the existing Air in very distant vesicles evenly in the liquid Mass is distributed so that sponge-like sealing inserts are obtained after the process can be deformed under pressure Liquid masses in which the air is in the form of large, irregularly distributed bubbles are present on the other hand unsuitable, since then strongly blown up, blistered sealing layers are created which are not satisfactory are deformable

The air can ζ B by stirring after production of the latex or by adding a separately prepared foam or soap sud Since this can easily introduce large air bubbles into the mass, this is shown in the example mentioned method preferred, in which the Air is supplied with the fillers It is eme well-known fact that large amounts of air are trapped by finely divided fillers, so that air in remote form with these in a Latex mass can be introduced The fillers can be added as a dry powder, if the latex is sufficiently stabilized, or you can first in a slogan of the stabilizer, ζ Β one Soap, can be stirred in. Wet the fillers with ordinary water before adding to the Latex is not cheap because of the enclosed air is displaced by water

The presence of air in the sealant Has another very important effect As mentioned earlier, the additives in latex sealants tend to be to a migration in the direction of the contact surface of the sealing compound and Lock when drying and coagulating like Usually carried out in the raw sealant existing air cells apparently act as a reservoir or as an air trap and hinder the Migration towards the shutter continues to prevent the air along with the relatively the small amount of rubber and the large amount of filler during drying

formation of a continuous rubber blade on the Surface of the seal Because of the open cell structure the water can easily escape from the mass, which enables very short drying times The rapid drying also prevents the migration of the stabilizers, so that the sealing inserts on the container closures are unusual stick firmly. The rapid evaporation of the water from the porous mass continues to provide sufficient Cooling effect so that the water does not boil even at high oven temperatures important to prevent boiling, otherwise the sealant will become blistered. Fast drying has even the further and very important advantage that the production tent as a whole shortened and the fuel consumption for the drying oven as well as the necessary oven area are significant It was found that the amount of air in the liquid mass is within quite Although according to the example, the amount of air 20 percent by volume of the liquid mass can be sufficient Inflation achieved with 5 to 10 percent air by volume when the air bubbles are very small. The upper limit is essentially determined by practical considerations, in general, is preferred flour more than about 30% air into the mass brought in

The proportion of rubber solids and fillers is not essential as long as the solids content of rubber is so small that the composition does not form an impermeable skin on drying. It has been found that in general a ratio of about 2 to 9 parts by weight of fillers per part of rubber solids is good Results

The one used as a stabilizer according to the example Ammonia soap serves a dual purpose. It decomposes when heated and thus works once as an additional blowing agent Die in the decomposition The released fatty acid reacts with the zinc of the hardener to an insoluble Zmkseife, which the Significantly increases the water resistance of the sealing material. Other substances, ζ Β ammonium soaps, can also be used other fatty acids and resin acids can be used.

Drying can be sufficient for puffing the mass and rapid coagulation in any case Temperature to be carried out In general, temperatures of 120 to 205 ° C are suitable, with those in the upright state, for example Sealing liners for 1.5 mm thick gaskets dry in a period of 1 to 3 minutes There are closures of buckets or larger vessels however, considerably thicker, e.g. 7.6 mm, and require drying times of 5 to 10 minutes On the other hand, those sometimes used for special sealing purposes can be very thin, for example Approximately 0.5 mm thick sealing inserts 30 seconds

The deposits must be in the dried sponge-like State easily compressible, so that when a pressure is applied eme solid, compact seal arises. Natural rubber latex is most suitable and therefore preferred. It can, however also other rubber latices or aqueous dispersions of rubber-like polymers are used, ζ B latices or aqueous dispersions of Butadiene - styrene - copolymers, butadiene - acrylonitrile copolymers, butadiene - styrene - acylnitnl terpolymers, Polychloroprene, polysulphide caoutchouc and butyl rubber.

To achieve optimal]
spongy Dichturigsmi

be dry, that is, at dun
lent deformation not m
5% and preferably mc
Contain moisture
salary is the liability of the
in the end significantly affected

Execution of the supplementary time as at most about it more than about 2 ° / o ; and a larger water seal on the et

The subsequent deforn
Seals is at a
which the cell structure completely
Down the pressure
of a specialist The temp

deformation -
warming is superfluous - ν
tempeiature or just a little
disturbance of the protective varnish
to avoid

The seals have noc
part that you get the spongy *
the respective sealing z
Seal can for example
Surface received or on
provided with a curvature
Deposits have such a good

Results must be practically complete

en or compressing the 'jerk carried out at dig wildly destroys the ι framework of ability aratur at night

there eme additional benefits at Zimmerdaruber to a Zerdem container lock

1 the additional pre

The ane can be completely flat The inner or outer edge is the seal Dimensional stability,

that they have the shape obtained by the deformation Maintain unlimited 1

Claims (2)

Claims 1 procedure for producing a seal from rubber or similar materials a container lock with which on the container lock eme equally infused with gas Dispersion of the raw material applied and heated and pressure to form a firm seal is deformed, characterized in that that the pressure deformation following the heating at the closure adhesive, dry, sponge-like sealant with an open pong structure under a sufficient pressure is applied to completely crush the cavities 2 The method according to claim 1, characterized in that the Dm
at most during 2 minutes
warmed and cold again is carried out under a pressure of ei (wa 23 kg / cm ²
3 Raw material made of rubber latex or similar materials for D marked by this Natural rubber Driving according to claim 1, net that the rubber latex latex is made with a fine-part filler and aqueous containing ammonia soap Dispersion is mixed 4 raw mass according to Ansj
indicates that the disp
weight ratio of fill
fabrics like 2 to 9 15 to:
contains Deformation ar of the sealing insert, which has been aged to around 193 ° C execution of the »Odor3, thereby erosion in a vessel [to rubber ^c est-) volume percent air 923 Considered
German Patent No.
British Patent No. 81 (
U.S. Patent No. 2,873 References: 390; 786; H81. 709 617/218 7 67 © Bundesdruckerei Berlin