EP4054945A1

EP4054945A1 - Rotary vacuum vessel closure with vessel closure seal

Info

Publication number: EP4054945A1
Application number: EP19824249.7A
Authority: EP
Inventors: Dany MÄNGEL
Original assignee: Actega DS GmbH
Current assignee: Actega DS GmbH
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2022-09-14
Also published as: KR20220109429A; MX2022005623A; CA3157090A1; MX2022005969A; CN115087600A; AU2020399074A1; AU2019477537A1; EP4055105A1; BR112022009450A2; KR20220107253A; JP2023505417A; ZA202203665B; JP7395736B2; CA3160233A1; CN114787277A; AU2019477537B2; US20220380098A1; JP2023505751A; ZA202204158B; US20230010622A1

Abstract

The invention relates to a rotary vacuum vessel closure, in particular for fat-containing filling materials, with a vessel closure seal comprising a polymer compound of which the seal consists substantially or entirely: a) wherein the polymer compound is PVC-free and comprises at least one TPS and at least one co-PP, b) and the polymer compound has a Shore A hardness (ASTM D2240, DIN ISO 7619-1) at 70°C between 30 and 85 and has an MFR (DIN ISO 1133, 5kg/190°C) of less than 20g/10 min.

Description

VACUUM VESSEL CLOSURE WITH VESSEL CLOSURE SEAL

The invention relates to a PVC-free vessel closure seal according to the preamble of claim 1.

A major problem with polymer-based vessel closure seals is the migration of seal components into the product. Migration problems arise particularly frequently with filling goods containing fat or oil, since the migrating substances such as e.g. B. Plasticizers and extenders are often fat-soluble.

Larger vessel closures of the type considered here are, in particular, rotary cam closures that are typically used to close screw-cap jars for food or beverages. These foods are often fatty products such as convenience foods, sauces, delicacies, fish in oil, antipasti, spice pastes and the like, the fat or oil content of which increases the risk that fat-soluble components of the packaging material will dissolve in the food. These requirements are also particularly relevant for baby food, which is typically sold in jars with Press-On Twist-Off® closures (also referred to here as PT closures or PT caps).

The vessel closures affected here usually have an opening width of at least 35 mm, e.g. B. 38 mm or more, e.g. B. 82 mm. Rotary cam locks may have 3, 4, 5 or more than 5 cams.

Conventional PVC-based container closures have favorable sealing properties. On the basis of soft PVC technology, it is also possible to formulate sealing compounds with low migration rates, which often use polyadipates. Due to their molecular weight, these tend to migrate less when in contact with fat.

The migration is assessed according to the rules defined in Regulation (EU) 10/2011 and DIN EN 1186. Especially for storage at

At room temperature it is postulated that the evaluation after a test time of 10 days at 40 ° C is sufficient to determine the migration. However, analytical practice teaches that these test conditions are not sufficient for plasticized PVC in sealing materials, but that migration limits are in some cases significantly exceeded after several months of storage at room temperature in contact with vegetable oil.

It is also undesirable to use PVC-containing compounds in packaging materials. The normal incineration of household waste produces acidic gases from halogen plastics, the escape of which into the atmosphere is harmful. In addition, even small amounts of PVC interfere with the material recycling of plastic waste. In addition, such PVC-based sealing elements require the use of plasticizers for reasons of unacceptable changes to the food and - in the case of the use of epoxidized soybean oil as a plasticizer - the potential formation of epichlorohydrins that have not been evaluated toxicologically are also questionable. There is therefore a need for PVC-free vessel closure seals which come as close as possible to the favorable properties of the known PVC-containing seals.

According to the invention, PVC-free compounds are used. In the product according to the invention, migration can largely or completely be avoided by dispensing with liquid constituents and / or by using polymers that are less susceptible to migration, as well as other measures.

The migration of components of the packaging (which may also include the sealing insert of the container closure) into the food is not only generally undesirable, but is also strictly regulated by legal provisions. Examples of such provisions are the EC Regulations 1935/2004, 2023/2006, (EU) 10/2011, including the amendments (EU) 321/2011, (EU) 1282/2011, (EU) 1183/2012, (EU) 202/2014, (EU) 174/2015, (EU) 2016/1416, (EU) 2017/752, (EU) 2018/79, (EU) 2018/213, (EU) 2018/831, (EU) 2019 / 37 and (EU) 2019/1338. At present, maximum quantities of 60 ppm of migrating components are permitted for food for small children.

The extent of any migration observed is measured using methods such as those defined in DIN EN 1186 in particular. Such methods are also used in the context of the present invention.

It is not a trivial problem to provide vessel closures of the type considered here with PVC-free sealing inserts if these closures have to comply with the regulations mentioned with regard to the possible migration of their chemical components. The sealing function must also be guaranteed under filling conditions.

The requirements for the sealing materials in the case of vessel closures for larger inner diameters (of at least 35 mm) of the vessel opening are more demanding because of the relatively larger amounts of material in the seal. For such purposes, it is particularly important to combine sufficient flowability of the polymer material in the manufacture of the sealing element with sufficient sealing properties in the closed state; this also includes the impermeability required today to prevent the ingress or escape of gases, possibly combined with an overpressure valve effect that prevents the vessel from bursting when heated or when overpressure develops in the vessel for other reasons. In addition, especially for the typical purposes of use of vessels with larger opening diameters (for example canned food), it is required that the sealing element can also be used under pasteurization and possibly even sterilization conditions. With all these characteristics, the seals must also meet the above requirements with regard to the possible migration of chemical constituents. A solution to these problems that has since been successfully introduced is disclosed in our application EP 09 756 681, now patent EP 2 470 435. The seal described there is PVC-free and is based on a combination of at least one olefin block copolymer (OBC) with at least one polyolefin elastomer (POE), high density polyethylene (HDPE) or polypropylene or propylene copolymer ((co -) PP). It should not contain a TPS. The Shore A hardness is between 45 and 95 at room temperature, the compression set (DVR) is between 30% and 90% at 70 ° C. The compression set is determined according to EP 2 470 435 as well as in the context of the present invention according to the ASTM D395-97 method B standard. In order to facilitate the processing of compounds previously known from EP 2 470 435, extenders and / or plasticizers were usually added to them. In particular, components that are liquid at application temperature such as extender oils or plasticizers (preferably white oil) were used for this purpose. However, in the known formulation according to EP 2 470 435, lubricants and components that are liquid at 20 ° C. are essentially dispensed with, since they can promote migration.

The product known from EP 2 470 435 is outstandingly suitable for many applications, but there is still room for improvement for some uses. In mechanical closing processes, the seal can be cut through if the closing path is very short and the machine can only be adjusted to a limited extent. In the case of very fast running machines, the steaming time is occasionally insufficient to warm up the closure sufficiently. It would therefore be desirable to have a seal that is thermally and mechanically more stable and at the same time softer than the seals known from EP 09 756 681. This is intended to achieve easier sealing with a lower risk of cuts. This seal should have the advantageous properties of the known seal as far as possible.

Seals should also have opening values that are as low as possible, so that twist locks such as twist-off locks (Twist-off ® locks), PT locks (Press-on Twist-off ® locks) and other screw locks can be opened easily. It must be ensured that the closure is not opened unintentionally, which is why the opening value cannot be too low.

With conventional 82 mm Twist Off ^® closures, the opening values of seals containing PVC are often in the range of 4.8 - 6.2 Nm (42-55 inch / lbs) or more. Technically complex Orbit ^® closures, with PVC-based seals with low migration values, which were developed to reduce the torque required for opening, are less than 4 Nm. With the known seal according to EP 09 756 681, typical opening values for Twist Off ^{® are} - Locks at 4.3-5, 1 Nm. A lower opening value would be an advantage for PVC-free closures.

The creation of such a seal is an essential object of the invention. In principle, the invention solves these and other objects by means of the combinations of features specified in the independent patent claims.

As with the solution according to EP 09756681, the disclosure of which we fully incorporate into the disclosure of this application by reference, the seal of the invention preferably comprises a polymer compound that is introduced into a sealing blank made of metal or plastic in a thermally sufficiently flowable form and there by stamping Or the like. Is brought into the desired shape, which it retains after cooling. In these cases, the finished seal usually consists entirely of the polymer compound. Machines for corresponding manufacturing processes are z. B. available from SACMI.

The terms "seal", "sealing insert" and "sealing element" are synonymous in the context of this description. In the case of the vessel closures according to the invention, the sealing element is designed in a similar manner as an insert on the inner surface of the vessel closure, as is the case with the known crown caps or screw caps In principle, the production method according to the invention is based on a metal vessel closure blank, which is preferably first pretreated on its inside with a suitable lacquer system. With a plastic vessel closure, this pretreatment is not necessary. The lacquer system usually consists of a base lacquer and an adhesive varnish, both of which can be based on an epoxy-phenolic resin system or (mostly for regulatory reasons) polyesters.

Lacquer systems from ACTEGA Rhenania (base lacquer TPE279 with adhesive lacquer TPE 1500 or ACTEcoat® TPE 515 with ACTEbond® TPE-655-MF), to which the most preferred compounds according to the invention adhere particularly well, are particularly suitable for this.

Alternatively, a suitable primer coating can be applied by lamination, lamination or possibly also by co-extrusion.

In some preferred embodiments, the polymer material which is to form the seal is applied to the inside of the blank pretreated in this way in a form rendered thermally flowable. In particular, an extrusion in which the sealing compound is placed in the temperature range between 100 ° C and 260 ° C is suitable for this. The extrusion can take place approximately in the middle of the inner surface of the blank if the sealing insert is to be designed in the shape of a circular disk. The metering of the polymer material for the extrusion takes place by stripping off a defined amount of the polymer compound at a nozzle. The sealing element is then preferably formed from the extruded, still flowable material by appropriate stamping (analogous to the known compression molding process).

Alternatively, the polymer material can be extruded as a strand and cut to size to fit, for example. The strand section obtained in this way is then inserted into the preheated closure blank and, if necessary, after further preheating, stamped into the sealing insert. A baking step can follow to increase the adhesion quality. The closure is then cooled. In other preferred embodiments of the invention, a melt ring can be extruded from sealing material, inserted into the blank by means of an applicator and shaped to form a seal, as described in US Pat. No. 9409324 B2.

While the known bottle caps (crown caps and the like) usually design the sealing element as a circular disk on the inside of the vessel closure, in the case of larger vessel closures such as according to the invention it can be advantageous to instead form only a ring made of polymer material, which is attached to the vessel when the vessel is closed The vessel wall is in contact with the opening area.

In a modified form, the sealing element can be formed outside the closure or closure blank by stamping a suitable polymer material and then introduced into the closure or blank. This process is also known from SACMI as outshell molding.

As the main component or only component, the material of the sealing insert comprises a polymeric component which comprises at least two different polymers, namely at least one TPS and at least one co-PP. The properties of this main polymeric component can be modified in a suitable manner by adding further components, for example further polymers.

The invention thus detaches itself from the concept known from EP 09 756 681, according to which the desired seal or the polymer compound of the seal must contain an OBC. An OBC can, but does not have to be included in the seal according to the invention.

An essential further difference in particularly preferred embodiments of the invention lies in the waiver of relevant contents of POUs. It has surprisingly been shown that POEs in the known seal can be replaced by other polymers. This waiver of POUs helps to solve a problem that occasionally occurs with the known seals: glass containers are usually end-of-line coated, for example by coating with PE waxes. When used with such glasses, seals with POE content can, under certain conditions, show a disruptive stickiness which undesirably increases the opening value of the closure.

In preferred embodiments of the invention, the seal therefore does not contain an analytically detectable content of POEs. In other preferred embodiments, there may be a low content of at least one POE, but this is kept so low that the opening value of the seal does not change significantly in comparison with an identical seal without POE content.

Furthermore, the invention breaks away from the concept according to EP 09 756 681, according to which the seal or the sealing compound must not contain a TPS.

The invention is based on the knowledge that thermally and mechanically stable, but softer seals of the generic type can be obtained if the polymer compound comprises certain types of TPS, in particular SEBS, in combination with certain types of co-PP. Not all known ones are suitable for this

Types of TPS and not all known types of co-PP, as will be described below.

In preferred embodiments, the polymer compound according to the invention additionally comprises at least one OBC and / or at least one

Polyolefin such as B. a polyethylene, especially LLDPE. The polyolefin can often be replaced by another polymer with similar physical properties. The polymer compound can optionally contain further polymers. It is preferably provided that the material of the sealing insert has only very low and particularly preferably no contents of components that are liquid at the application temperature. The application temperature is usually the same as the ambient temperature, i.e. in the range of normal ambient temperatures outdoors or in heated rooms. Typically the application temperature is 20 ° C.

Therefore, preferably only small amounts or preferably no amounts of liquid extenders such as, in particular, white oil are added to the material of the sealing insert.

The material preferably contains no more than 10%, preferably no more than 7%, in particular no more than 4% or even no more than 1% of lubricants, in particular those that are restricted to a migration test at 40 ° C for 10 days Fatty fillings pass over (percentages in this application are always percentages by weight, based on the total weight of the compound in the seal, unless expressly stated otherwise). Polymer compounds according to the invention generally have a Shore A hardness (ASTM D2240, DIN ISO 7619-1) at 70 ° C. between 30 and 85, more specifically between 40 and 75. The lower the hardness, the easier it is to attach the closures. When used on steam vacuum sealing machines, there is an increased risk of cuts if the hardness is below Shore A 30 at 70 ° C. Above Shore A 85 there is an increased risk that the closure will not succeed. When used on cold vacuum sealing machines without preheating, no vacuum is achieved with Shore A above 85. The compression set of the polymer compound (23 ° C., ASTM D395-97 method B) is preferably a maximum of 50%, more preferably a maximum of 40% and particularly preferably a maximum of 30%. The DVR can be 25% or less in optimized embodiments. The polymer compound preferably has a relatively high viscosity in the melt, ie a melt mass flow rate (MFR) according to DIN ISO 1133 at 5kg application weight and 190 ° C measurement temperature of less than 20g / 10 min., Better less than 15g / 10 min. Specifically For processing on cold vacuum sealing machines, it can make sense to set other viscosities.

After closing, during and after the cooling process and often also during storage of the closed container, PVC-free compounds lead to crystallization processes in the polymer compound. These influence the hardness and elasticity of the seal, thus the tension between closure and container, and the migration of the lubricant on the surface of the seal. The slower the crystallization, the lower the tension because the polymer compound has more time to relax. The smaller the crystalline content in the compound, the more favorable the migration of the lubricant will be.

The crystallinity of the polymer compound can be measured using known methods that provide values for the crystallinity area, the beginning and end of the crystallization process and maximum crystallinity.

The peak crystallization temperature and the enthalpy of crystallization based on the weight is determined by DSC measurement (dynamic scanning calorimetry) from the first cooling curve. The rules for this are described in the ISO 11357 standard or its sub-chapters (in particular IS011357-3). The sizes were measured using a DSC1 system from Mettler Toledo.

It has proven helpful for describing the suitability of a sealing material for vacuum rotary closures to design polymer compounds in such a way that the temperature of the exothermic peak is higher than the expected maximum operating temperature of the vessel closure. This exothermic peak temperature from the crystallization process is partly well below the temperature of the endothermic melting peak. In principle, the invention prefers the use of polymers which have low enthalpies of crystallization, while particularly crystalline polyolefins such as homo-PP, LLDPE, LDPE and HDPE are preferably not used or only used to a reduced extent.

Preferred polymer compounds have a specific total enthalpy of crystallization above room temperature of less than 50 J / g, particularly preferably a maximum of 40 J / g, more preferably a maximum of 30 J / g. The TPS used according to the invention are preferably SEBS. In general, linear SEBS with styrene contents between 26% and 34%, especially between 29% and 33%, are preferred. Most preferred are SEBS with 31% to 32% styrene. Particularly preferred SEBS are linear triblock copolymers of the SE / BS type. Particularly suitable are products such as KRATON® G1651 and Calprene ^® 6174. SEBS polymers having lower styrene contents than 25 wt%, and at the same time low molecular weights than the above reference materials may be used in admixture with KRATON ^® G1651, to (in the sense of a plasticizer in place of White oil) the flexibility and flowability of the

Increase Compounds.

Other TPS that can be used in place of or in conjunction with SEBS include SEEPS, polybutenes, and similar TPS.

Preferred polymer compounds generally comprise up to 60%, more particularly up to 55%, more preferably up to 50% TPS. Preferably include those

Polymer compounds at least 1%, especially at least 5% and more preferably at least 10% TPS. Other preferred embodiments comprise at least 20%, more preferably at least 30%, and most preferably at least 40% TPS.

Preferred TPS generally have styrene contents of 28 to 35%. A 10% solution in toluene has a viscosity of less than 2.5 Pa.s, measured with a Brookfiled LVT viscometer. The density is preferably between 0.90 and 0.93 g / ccm.

TPS are not per se particularly suitable polymers for sealing compounds that come into contact with greasy or oily fillers, because they facilitate the entry of fats and oils into the seal. This is especially true for products that are thermally treated, e.g. B. pasteurized or sterilized. According to EP 09 756 681 there is a need to dispense with TPS contents in the polymer compound as completely as possible.

However, it has surprisingly been found that TPS can also be used successfully in sealing compounds for applications in fats and oils if the polymer compound contains certain polypropylene copolymers (co-PP). Apparently the co-PP content prevents the absorption of fats and oils through the seal even in the presence of TPS and also during pasteurization and even sterilization (up to temperatures of 132 ° C). This can also be achieved if homo-PPs are used, which, however, do not lead to the required physical properties of the seal in such TPS-based compounds. Homo-PPs are therefore not used instead of co-PPs in preferred embodiments of the invention.

Preferred co-PPs have a Shore D hardness of less than 55, preferably below 45, particularly preferably below 40. The Shore D hardness is preferably greater than 15, better than 20, particularly preferably greater than 30.

The MFR of the co-PP is preferably 2.16 kg and a measurement temperature of 230 ° C, less than 30 g / 10 min, more preferably less than 20 g / 10 min and even more preferably below 10 g / 10 min.

Particularly preferred are co-PPs with an MFR (2.16kg / 230 ° C) of at least 0.1, more specifically at least 0.3 and even more specifically at least 0.5, and a maximum of 15, more specifically a maximum of 12 and even more specifically a maximum of 10.

The melting point of the co-PP is preferably below 165 ° C, more preferably below 160 ° C, most preferably below 150 ° C.

The amount of co-PP used in the compound is preferably generally 5% -65%. Higher levels are possible.

The co-PP preferably has a low crystallinity with a relatively high melting point. Preferred co-PPs have a total enthalpy of crystallization of less than 50 J / g, with melting points above 135 ° C, or even above 160 ° C.

Particularly suitable products can be found in the portfolio of the LyondellBasell ADFLEX series or at Mitsui Chemicals in the TAFMER series. VISTAMAXX grades from ExxonMobil are also suitable.

In preferred embodiments of the invention, the co-PP can be partially replaced by other polymers, for example by LLDPE.

The polymer materials can withstand hot filling of up to 100 ° C for up to 60 minutes.

Optionally, pigments, preferably inorganic pigments, can also be added to the formulations of the compounds in order to exclude pigment migration. It has also been shown that other additives such as (unsaturated) fatty acid amides, waxes, silicones and other common additives can be added to the polymer compounds, for example in order to improve processing and the performance properties. In the following, exemplary embodiments of the invention are described on the basis of the composition of the polymer compounds from which the vessel closure seal according to the invention was formed as indicated above: Exemplary embodiment 1:

40% co-PP 10% SEBS 47% OBC 3% lubricant

Example 2:

30% co-PP 40% SEBS 30% LLDPE

Example 3:

60% co-PP 40% SEBS

Claims

1. Vacuum vessel screw cap, in particular for filling goods containing fat, with a vessel closure seal comprising a polymer compound of which the seal consists essentially or entirely, a) the polymer compound being PVC-free and comprising at least one TPS and at least one co-PP, b ) and the polymer compound has a Shore A hardness (ASTM D2240, DIN ISO 7619-1) at 70 ° C between 30 and 85 and an MFR (DIN ISO 1133, 5kg / 190 ° C) of less than 20g / 10 min .

2. Vacuum container screw cap according to claim 1, in which the polymer compound comprises essentially no POE.

3. Vacuum vessel screw cap according to claim 1 or 2, in which the

Polymer compound essentially does not include homo-PP.

4. Vacuum vessel screw cap according to one of claims 1 to 3, in which the

Polymer compound comprises at least one SEBS, SEEPS or polybutene.

5. Vacuum vessel screw cap according to one of claims 1 to 4, in which the

Polymer compound comprises a linear SEBS with styrene contents between 20% and 40%, preferably with styrene contents between 26% and 34%, especially between 29% and 33%, and most preferably with 31% to 32% styrene.

6. Vacuum vessel screw cap according to one of claims 1 to 5, in which the

Polymer compound comprises at least 1%, especially at least 5% and more preferably at least 10% TPS or 20%, more preferably at least 30% and most preferably at least 40% TPS.

7. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound comprises a TPS with a Shore A hardness (ASTM D2240, DIN ISO 7619-1) at 23 ° C of 50 to 90, preferably 55 to 80.

8. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound is a co-PP with a Shore D hardness (ASTM D2240, DIN ISO 7619-1) at 23 ° C of less than 55, preferably below 45, particularly preferred below 40 and greater than 15, preferably greater than 20, particularly preferably greater than 30.

9. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound is a co-PP with an MFR of less than 30, more preferably less than 20, even more preferably less than 10 g / 10 min measured at 2.16 kg / 230 ° C includes.

10. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound is a co-PP with MFR (2.16kg / 230 ° C) of at least 0.1, more specifically at least 0.3 and even more specifically at least 0.5, and a maximum of 15, more specifically a maximum of 12 and even more specifically, includes a maximum of 10.

11. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound comprises a co-PP with a melting point of the co-PP below 165 ° C, more preferably below 160 ° C, most preferably below 150 ° C.

12. Vacuum container screw cap according to one of the preceding claims, in which the polymer compound comprises between 1% and 80%, preferably between 5% and 65% co-PP.

13. Vacuum container screw cap according to one of the preceding claims, in which the polymer compound comprises at least one further polymer, in particular LLDPE.

14. Vacuum container screw cap according to one of the preceding claims, in which the polymer compound contains no more than 10%, preferably no more than 7%, in particular no more than 4% and particularly preferably no more than 1% of lubricants.

15. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound contains no more than 10%, preferably no more than 7%, in particular no more than 4% of components that are liquid at 20 ° C.

16. Rotary vacuum vessel closure according to one of the preceding claims, which can be pasteurized, preferably also sterilized.

17. Vacuum vessel screw cap according to one of the preceding claims, which shows a vacuum retention.

18. Vacuum vessel screw cap according to one of the preceding claims, in which the polymer compound has a compression set at 23 ° C (ASTM D395-97 method B) of a maximum of 50%, more preferably a maximum of 40% and particularly preferably a maximum of 30%.