AU599675B2

AU599675B2 - Moulding

Info

Publication number: AU599675B2
Application number: AU75155/87A
Authority: AU
Inventors: Dieter Grundschottel; Peter Nussen; Horst H. Peifer
Original assignee: DS Chemie GmbH
Current assignee: Actega DS GmbH
Priority date: 1986-06-20
Filing date: 1987-06-19
Publication date: 1990-07-26
Anticipated expiration: 2007-06-19
Also published as: FI880319A; FI880319A0; ES2037745T3; WO1987007903A2; EP0250057A3; DE3784033D1; ATE85354T1; AU7515587A; EP0270624B1; DK87188A; EP0270624A1; ZA874428B; DE3620690A1; DE3620690C2; FI90347B; EP0250057A2; DK87188D0; WO1987007903A3

Abstract

Moulding, in particular sealing element, for mechanically sealing bottle and jar closures made of metal or plastic, consisting of a synthetic halogen-free polymer compound elastically deformable in normal conditions of use, with a styrene-butadiene-styrene-rubber (SBS-rubber) content, and containing an ester-group-free hardness modifier, whereby the Shore A hardness of the polymer compound is between 30 and 80. The polymer compound also contains an aliphatic polymer, in particular polyethylene and/or an ethylene-vinyl acetate copolymer. The polymer compound is in particular suitable as an insert for vessel closures, such as capsules and screw cups.

Description

PCT

1 I trailaiAWgfr INTERNATION1sALE ANMELDUNG VE(1FNI A' ISRAG @GBER DIE INTERNAT1ONA 1 E ZUSAMMENARBEIT AUF DEM GEBIE DEVAETESENS (PCT) (51) Internationale Paten tklassit ation 4~ C08L 23/02,53/02 (11) Internationa'q- Veoutiffentichungsnurmcr: WO 87/ 07903 A2 (43) Internationales Veriiffcntlichungsdatum: 30. Dezember 1987 (30.12.87) (21) Internationales Aktenzeichen: PCT/EP87/003161 (22) Internationalcs Anineldedatum: 19. Juni 1987 (19,06,87) (31) Priorit~itsaktcnzeichcn: (32) Prioritlitsdatumn: (33) Priori titsland: P 36 20 690.3 20. Juni 1986 (20,06,86)1 (71) Anmelder, DS-CHEMIE GMBHI CO 'G EDE/DE]; Cuxhavener Strage 42-44, D-2800 Brerrcn (DE).

(72) Erfinder: PEIFER, H-orst. H. ;Viehrejhe 42, D-2804 Lilienthal GRUNDSCHOTT7EL, Peter Schaphuser Dorfstrasse 30, D-2806 Oyten NCJSSEN, Peter Buchenhuegel 30, D-2863 Ritterhude-Ihipohl

(DE).

(74) Anwalt: EISENFOHR SPEISER; Martinistr. 24, D- 2800 Bremen I (DE).

(81) Bestimmungsstaaten, AT (europflinches Patenit), AU, BE (europfiisches Patent), CR (europa.isches Patent), DE (europflisches Patent), DK, 171, FR (europlisches Patent), GB (europltisches Patent), IT (europiiisches Patent), LU (europiiisches Patent), NL.(europltisches Patent), SE (europllisches Patent).

VeriifFentllcht Oline in ternationalen Recherchenbericht und erneut zu verbffenttichen nach Erhalt des Benich Is.

j. 8 F EB 1983

AUSTRALIAN

12 JAN 1988 IPATENT

OFFICE]

(54) Title: MOULDING (54) Bezelchnung: IFORMTEIL (57) Abstract Moulding, in particular sealing element, for mechanically sealing bottle and jar closures made of metal or plasti.,, consisting of a synthetic halogen-free polymer co~mpound elastically deformable in normal cond'tions of use, wvith a s:'yrene-b utad iene-styrene- rubber (SBS-rubber) content, and containing an ester-group-free hardnews modifier, wh~ereby '.he Shore A hardness of the polymer compound Is between 30 and 80, The polymer compound also contains an alityhaio polymer, in particular polyethylene and/or an ethylene-vinyl acetate copolymer. Thrb polymer compound is in particu~ae suit able as an insert for vesel zlosures, ,lch as capsules and screw cups.

(57) Zusamnienfassung Ein Fornvtell, insbesondere Dichtungselement, for mechanism dichtende Flaschen- und Glllserverschltlsse aus Metail oder Kunststoff, bestehend aus einem unter (lblichen Verwendlungsbedingtlngen elastiscb verformbaren syntheti'schea halogenfreien Polymercom pound, mit elnem Gehalt an StyroI- Butadien-Styro I.Kau tschv'k (SBS-Kautwchuk) Lind einem Gehalt an elnem estergruppenfreien l-iirtemodifikator, Nvobei die Shore A.lirte des Poiymercompoua~s zwischen 30 und liegt. Das Polymercompound hat au~erdem elnen Gehalt an einemr aliphatischen 1'olyter, insbesondere Polyethylen und/oder Ethylen-VinylacettCopolymer, Das Polymercompotind eignet sich insbesondere als Inneneirnlage ftlr Gefiiverschlflsse wie Kronenkorke und 1

MOULDING

Description The invention relates to a moulding, in particuler a sealing element for vessel closures, of a synthetic polymer compound which is elastically deformable in normal conditions of use and, if appropriate, has a filler content. The inveintion further relates to a polymer compound for the production of mouldings, in particular of sealing elements for vessel closures which can be moulded plastically, in particular thermoplastically, into the moulding, but i elastic in its usual conditions of use and contains a synthetic polymer, a hardness modifier, and, if appropriate, foaming agent and/or filler or processing aid. In addition, the invention relates to a vessel closure, in particular a crown cork or bottle screw closure, with an inner insert of elastic polymer material.

Ve3sel closures must be suitable for being fitted on the vessel simply and nevertheless with a relIiable seal, while usually no secondary treatments should be necessary and the dimensions of the vessel opening and its state of conservation and roughness (for example in the case of returnable bottles) may vary a great deal. It has therefore already been known for a long time to provide vessel closures, such as for example crown corks, with an elastic sealing element on their inside facing the vessel, which sealing element is pressed between the closure and the vessel when the closure is fitted and ensures tightness.

While formerly the inserts of crown corks or bottle screw closures were predominantly made of press cork which was, if appropriate, also coated with a thin plastics film or aluminium foil, the sealing element has for some time been produced completely from synthetic polymer compound. However, only polymer compounds which are durable and resistant enough and at the same time have the necessary elasticity are suitable for this.

In practice, PVC is mainly used for this; i~ iCL;.i =1_ 2 polyethylene and mixtures of these substances with vinyLacetate or vinylacetate-ethylene copolymers have also been used.

The production of vessel closures with the use of such polymer compounds is described for example in German Auslegeschrift 2,033,064 and German Offenlegungsschrift 3,021,488.

However, these known polymer compounds still have considerable disadvantages. The use of PVC or other halogen-containing plastics leads to ever increasing difficulties in the disposal and neutralization of the used vessel closures finding their way into household refuse. In the usual incineration treatment of household refuse, halogen plastics produce acid-containing gases, the release of which into the atmosphere is harmful. The addition of Low molecular weight plasticizers (for example phthalates), indispensable for adjustment of the required sealing properties, is not harmless either, for reasons of health care, since these plasticizers are partially released again from the PVC and can find their way into the human body via foodstuffs or semiluxury products contained in the vessel. For this reason, the proportion of plasticizer in such polymer materials is set upper limits by corresponding regulations.

Polyethylene alone is unsuitable as a sealing material in particular if temperature fluctuations or damaged vessel mouths have to be taken into account.

Polyethylene is, in addition, not suitable, for reasons of tightness, for CG2-containing beverages.

The object of the invention is therefore to specify a moulding, a polymer compound for its production and a vessel closure fitted therewith, of the type mentioned at the beginning, which ensure, with inexpensive production, the necessary tightness of the vessel closure, do not contain any harmful substances, in particular no halogen-containing constituents and no low molecular weight ester-group-containing plasticizers, and can withstand the load conditions of usual vessel closures, for example a

CN>,~

i, -3pasteurizing operation.

According to a first embodiment of this invention there is provided a moulding for mechanically sealing bottle and jar closures of metal or plastic, consisting of a synthetic halogen-free polymer compound elastically deformable in normal conditions of use, containing styrene-butadlene-styrene rubber (SBS rubber) and an ester-group-free hardness modifier, the Shore A hardness of the synthetic halogen-free polymer compound being between 30 and 80 and the synthetic halogen-free polymer compound containing an aliphatic polymer.

According to a second embodiment of this invention there is provided polymer compound for the production of mouldings for vessel closures, which can be moulded plastically into a moulding which is elastic in normal conditions of use, and contains a synthetic polymer, a hardness modifier, as well as, if appropriate, foaming agent and/or filler or processing aid, the polymer compound being substantially halogen-free and containing a) styrene-butadiene-styrene rubber (SBS rubber) with a Shore A hardness of between 40 and b) an ester-group-free hardness modifier, and c) an aliphatic polymer, and 0 d) having Shore A hardness of between 30 and According to a third embodiment of this invention there Is provided a S* vessel closure with an inner insert of elastic polymer material, characterized in that the inner insert is substantially halogen-free and contains styrene-butadiene-styrene rubber (SBS rubber), an ester-group-free hardness modifier and an aliphatic polymer, and its Shore A hardness is between 30 and The polymer compound according to the invention can be produced from easily obtainable raw materials, It can be processed by means of the machines already available for the processing of comparable PVC materials, eg. produced by the SACMI Company, Italy- The addition of a foaming agent, which effects a certain widening of the extrudate when the polymer compound is discharged from the extruder, substantia.ly corresponding to the behaviour of PVC compounds under the same conditions, proves advantageous in this case. To improve the cutting and transporting behaviour of the polymer compound, a small content of highly dispersed silicic acid may advantageously be provided. The plasticized polymer compound can be KEH/0061f il I~amnuoY-~in~PPli~flil~ 3A extruded, cut and subsequently compression-set without difficulties. It then hardens into the desired moulding, This moulding, produced from the polymer compound and either adhering to the vessel closure or Inserted in it has, with good dimensional stability, an elasticity which is adequate to ensure tightness for all usual applications of vessel closures. The vessels can undergo pasteurization with fitted closure, without the sealing moulding suffering or leaking.

Since the polymer compound does not contain any low molecular weight plasticizers, it is harmless from the point of view of foodstuffs law; if It finds its way into household refuse, it cannot release any harmful acid gases In a refuse incineration plant, since it is S o nt .4444 4* 4* 44 4 *4* 4*44 4 9 4 KEH/006 if 4haLogen-free.

The vessel closures according to the invention comply with regulations, such as are specified for example in DIN Standard 6099 for crown corks.

It goes without saying that the polymer compound according to the invention can be adapted to the particular requirements of various applications by its composition being appropriately chosen. For instance, the elasticity can be influenced by means of the total proportion of additives which modify the initial hardness of the SBS used. The proportion of foaming agent and the degree of foaming effected thereby also allows an adaptation of the material properties.

The use of the polymer compound according to the invention has the further advantage that the mouldings produced can be lighter than known sealing elements, for example of PVC. With the polymer compound according to the invention, for example inner inserts for crown corks which weigh only approximately 150 to I 2s50 D P r e-c fcib1 Ics i n 2c, c' 1J6,1 mg) can therefore be produced; this means a not inconsiderable material saving in comparison with known inner inserts of PVC.

It is necessary in particular for mechanically sealing bottle and vessel closures of metal or plastic, such as for instance crown corks and screw caps, that the sealing element forming the insert adheres to the closure firmly and over its full area. Otherwise, if vessel mouths are damaged, displacement or twisting of the insert may occur, and consequently so may leakages.

In addition, if there is poor adhesion of the insert, local detachments cause moisture-filled bubbles which promote the corrosion of metal closures. These disadvantageous effects are effectively suppressed by the PE or EVA content of the compound.

The use of PE-containing and/or EVA-contairing compounds has the .advantage that contents of aromatic polymers in the compound are reduced or avoided completely. Styrene derivatives, which are occasionally .4I 5 contained In similar compounds, can influence odour and taste of the packed product disadvantageously.

A lower concentration of aromatic polymers increases the processing reliability, in particular at relatively high temperatures, by suppressing the occurrence of undesired monomers or degradation products.

For the filling of carbonated liquids, it appears necessary in future t"at the sealing element performs a safety valve function, Ie, allows an escape of the gas at a certain excess pressure In order to avoid a bursting of the vessel. This Is made possible by the plastic properties of PE-containing compounds according to the invention.

The invention is further elucldated below with reference to an exemplary embodiment, which concerns an :nner insert for a crown cork.

For this, firstly a polymer compound Is prepared by mixing styrene-butadiene-styrene rubber (SBS rubber) with a medicinal grade, substantially paraffinic white oil (DAB 8 quality) and additives of polyethylene ethylene-vinylacetate copolymers (EVA) and, if appropriate, vinylacetate-ethylene copolymers (VAE) and/or polystyrene.

The SBS rubber, which in itself has a Shore A hardness of between 40 and 90, forms the main constituent here. The content of the other polymers ,0 does not exceed 50% by weight of the total polymer compound and, fcr usual S crown corks, is lower, but preferably not below 5% by weight.

As well as these constitutents, between 0.05 and 3% by weight, preferably foaming agent and up to 5% by wei(ht,, preferably less than 1% by weight, highly dispersed SiO 2 are also added to the polymer compound. Preferably the foaming agent is azodicarbonamide.

The polymer compound produced in this way is fed to a known machine as is also used for the inside coating of, for example, crown cork capsules, with PVC-containing polymer materials.

In this machine, the polymer compound first passes into an extruder, in which It is further homogenized by thorough kneading. It leaves the die orifice of KEH/0061f _li _i L. ~I 1 ii ll~iU~aYLll~j~ 6 the extruder as a plastic extrudate, which is cut up directly after the die orifice into individual Lumps.

These Lumps, which each weigh approximateLy 150 to 170 mg, are in each case transferred onto the inner surface of a metal capsule, which forms the body of the crown cork. The still plastic polymer compound is spread over this innsr surface, if appropriate pretreated to promote adhesion, by a ram and stamped tc form a thin, approximateLy disc-Like moulding. At the same time, it is possible to form any annuLar projections of the moulding which may be desired, which embrace the bottle rim in the mouth region when the crown cork is fitted.

After cooling and hardening of the thermoplastic polymer compound, the moulding forming the inner insert of the crown cork is no longer plastically deformable in normal conditions of use, but can bear elasticalty with sealing effect against the bottle rim if the crown cork is pressed onto the bottle. Owing to its elasticity, the moulding can thereby compensate for unevennesses (for example due to damage) and also for the roughness of the bottle rim caused by production tolerances.

By suitable choice of the constituents added for hardness modification, the polymer compound of the moulding may be designed in such a way that it withstands even the elevated temperature which occurs during bottle pasteurization.

The crown cork produced in this way is ready for use after hardening of the polymer compound and may be stored until its use; the properties of the mouLding which forms its inner insert do not change even over lengthy perlids.

It goes without saying that, apart from the use presented here in conjunction with crown corks, other sealing elements for vessel closures can also be produced in wh'ch the corresponding moulding is not solidly .onnected to the closure body.

Claims

7- The claims defining the invention are as follows: 1. Moulding for mechanically sealing bottle and jar closures of metal or plastic, consisting of a synthetic halogen-free polymer compound elastically deformable in normal conditions of use, containing a styrene-butadiene-styrene rubber (SBS rubber) and an ester-group-free hardness modifier, the Shore A hardness of the synthetic halogen-free polymer compound being between 30 and 80 and the synthetic halogen-free polymer compound containing an aliphatic polymer. 2. Moulding according to claim 1, characterized in that said moulding Is a sealing element. 3. Moulding according to claim 1 or claim 2 characterized in that the aliphatic polymer is polyethylene (PE) and/or ethylene-vinylacetate copolymer (EVA). 4. Moulding according to any one of c'aims 1 to 3, characterized in that the hardness modifier is a mineral oil. Moulding according to claim 4 characterized In that the mineral oil is a refined, medicinal grade, substantially paraffinic white oil. 6. Moulding according to any one of claims I to 5 characterized in that the content of polymer substances other than SBS does not exceed by weight of the polymer compound. 7. Moulding according to claim 6, characterized in that the content of polymer substances other than SBS Is not less than 5% by weight of the polymer compound. So 8. Moulding according to any one of claims I to 7, characterlzed in that the polymer compound Is foamed.
9. Moulding according to any one of claims I tv 8, characterized in that the polymer compound contains silicon dioxide $102. Moulding according to claim 9, characterized in that the Sio, content makes up at most 5% by weight based on the polymer compound as a whole.
11. Moulding according to claim 10, characterized In that the SlO Z content Is less than 1% by weight based on the polymer compound as a whole.
12. Moulding according to any one of claims to 11 characterized in that its Shore A hardness is between 40 and
13. Moulding according to any one of claims I to 12 characterized In that It is designed as a substantially disc-shaped inner insert of a crown cork or bottle screw closure and weighs between 150 mG and 250 mg. "KEH/0061f 1 r r 3 8
14. Moulding according to claim 13 characterized in that it weighs less than 200 mg. Polymer compound for the production of mouldings for vessel closures, which can be moulded plastically into a moulding which is elastic in normal conditions of use, and contains a synthetic polymer, a hardness modifier, as well as, if appropriate, foaming agent and/or filler or processing aid, the polymer compound being substantially halogen-free and containing a) styrene-butadlene-styrene rubber (SBS rubber) with a Shore A hardness of between 40 and b) an ester-group-free hardness modifier, and c) an aliphatic polymer, and d) having Shore A hardness of between 30 and
16. Polymer compound according to claim 15 characterized in that the moulding produced is a sealing element. S, 17. Polymer compound according to claim 15 or claim 16 characterized S in that the polymer compound can be moulded thermoplastically.
18. Polymer compound according to any one of claims 15 to 17 characterized in that the aliphatic polymer is a polyethylene (PE) and/or K ethylene-vinylacetate copolymer (EVA).
19. Polymer compound according to any one of claims 15 to 18, characterized in that the hardness modifier is a mineral oil. Polymer compound according to claim 19 characterized in that the mineral oil is a refined, medicinal grade, substantially paraffinic white oil.
21. Polymer compound according to any one of claims 15 to S characterized In that the content of polymer substances other than SBS does not exceed 50% by weight of the p^lymer compound.
22. Polymer compound according to claim 21, characterized in that the content of polymer substances other than SBS is not less than 5% by weight.
23. Polymer compound according to any one of claims 15 to 22, characterized by a content of a foaming agent of between 0G05 and 3% by weight and/or a content of highly dispersed SIO 2
24. Polymer compound according to claim 23 characterized by a content of foaming agent of 0.1% by weight. H 01f I^ i rfoO~1 f ~1 Pr;l_~jl--FTr;1 _li- 0 -9- )lymer compound according to claim 23 or claim 24, characterizod in that the foaming agent Is azodicarbonamide.
26. Polymer compound according to any one of claims 23 to characterized by a content of highly dispersed S10. which does not exceed by weight.
27. Polymer compound according to claim 26 characterized by a content of highly dispersed SIO of less than 1% by weight.
28. Vessel closure with an inner insert of elastic polymer material, characterized in that the inner insert Is substantially halogen-free and contains styrene-butadiene-styrene rubber (SBS rubber), an ester-group-free hardness modifier and an aliphatic polymer, and its Shore A hardness is between 30 and
29. Vessel closure according to claim 28 characterized In that the vessel closure is a crown cork or bottle screw closure. Vessel closure according to claim 28 or claim 29 charactertzed in that the alipatic polymer is a polyethylene and/or ethylene-vnylacetate copolymer (EVA).
31. Vessel closure according to any one of claims 28 to characterized in that the Shore A hardness of the inner insert is between and 70 and the inner insert weighs between 150 mg and 250 mg.
32. Vessel closure according to claim 31 characterlzed in tthat the inner Insert weighs less than 200 mg.
33. Vessel closure according to any one of claims 28 to 32, characterized in that the hardness modifier is a mineral oil fraction.
34. Vessel closure according to clain, 33 characterized in that the mineral oil fraction is a refined, medicinal grade, substantially paraffinic white oil.
35. Vessel closure according to any one of clalms 28 to 34, characterized in that the Inner Insert is foamed andlor contains slUlcone1 d oxide.
36. Vessel closure according to any one of claims 28 to characterized in that the inner insert is formed by moulding a polymer compound according to any one of claims 15 to 27 oft tlhe Inner surface r? C,4 closure body, if appropriate treated to promote adhesion.
37. A moulding for mechanically sealing bottle and jar closures f metal or plastic, as defined in claim I and substantially as hereinbef, KEH/0061f l I I I II I i I IT I1 I 1 l I 10 descri bed.
38. A closures, as descri bed,
39. A material as described. polymer compound for thp Production of nmouldings for vessel def ined i n claim 15 and substantial ly as hereinbefore vessel closure with an Inner insert of elastic polymer definu,"d in claim 28 and substantially as hereinbefore C C C CC C CC9 C C C C C #CI C C C C. C 4 CC C C *1 C CCC CC,. DATED this SECOND day of MAY 1990 DS-Chemle GmbH Co K.G, Patent Attorneys for the Appli.;ant SPRUSON FERGUSON _.KEI/OO61f