CN106009139B

CN106009139B - Sealing liner, container closure and polymer composite therefor and use

Info

Publication number: CN106009139B
Application number: CN201610343954.1A
Authority: CN
Inventors: 克里斯蒂亚娜·波尔; 乔治·施伦克; 吕迪格·维滕贝格
Original assignee: Actega DS GmbH
Current assignee: Actega DS GmbH
Priority date: 2009-11-20
Filing date: 2009-11-20
Publication date: 2020-09-11
Anticipated expiration: 2029-11-20
Also published as: CN106009139A

Abstract

The invention relates to a sealing gasket, a container closure and a polymer composite for the same and applications. The polymer composite is a polymer composite for a sealing liner of a container closure, in particular for a fat-containing filling, the polymer composite being configured such that migration of the composite components into the filling is reduced, characterized in that the polymer composite has a shore a hardness of between 45 and 95 and the polymer composite exhibits a compression set (DVR) of 30% to 90% at 70 ℃ in a compression set test similar to ASTM D395-97 method B.

Description

Sealing liner, container closure and polymer composite therefor and use

The present patent application is a divisional application of the patent application with application number 20098016254.6 (international application number PCT/EP2009/008273) and the title "polymer composite sealed with a fat-containing filler" filed on the filing date of 2009, 11/20.

Technical Field

The invention relates to a polymer compound for a sealing liner of a container closure (made of metal or plastic) for a container which contains a filling material, in particular a fat-containing filling material, said polymer compound being designed such that migration of the sealing part components into the fat-containing filling material is reduced.

Background

Larger container closures of the type considered here are in particular lug lids, which are typically used for packaging screw-top cans for food or beverages. The food often relates to fat-containing products such as prepared foods, condiments, delicatessens, fish in oil, savoury foods, spice pastes and the like, the content of which fats or oils increases the risk of the fat-soluble components of the packaging material dissolving into the food.

These requirements typically have a Press-on (Press-on)

) Of particular importance in baby food products sold in cans in the enclosure.

The industry has long used PVC-free compounds for sealing gaskets for crown caps or narrow-neck screw closures, while PVC-containing compounds have been used as they are for screw caps and the like for container closures for containers having larger internal diameters. Typically, such PVC-containing compounds are applied in fluid form at room temperature, in the form of a plasticizer-containing system.

Sealing materials with less migration, which often use polyadipates, can be prepared on the basis of soft-PVC technology. The sealant is less prone to migration due to its molecular weight, however, to our knowledge, toxicity analysis of degradation products formed especially in the stomach has not been performed to date. The specified experimental method for analyzing migration EN1186 assumes: the migration was completed after 10 days at 40 ℃ storage. The teaching of analytical practice is that this is not the case in the case of PVC softening, even if the closure exceeds the migration limit after a few months, while observing the test conditions. Preferably, a PVC-free compound is used according to the invention. This effect is prevented in the product according to the invention by omitting the fluid component.

However, the use of PVC-containing compounds in packaging materials is undesirable. In the incineration of household waste in general, acid-containing gases are generated from halogen-containing plastics, which are harmful for release into the environment. In addition, small amounts of PVC have interfered with material recycling of plastic waste. Furthermore, such PVC-based sealing elements require the use of plasticizers, which are likewise feared by unacceptably altering the foodstuffs. Furthermore, in recent years there has been public discussion surrounding the use of additives and their decomposition products in PVC seals. Examples here are 2-ethylhexanoic acid, which is usually derived from a stabilizer, and semicarbazides which can be formed from exothermic blowing agents, such as azodicarbonamide. These materials have also been found in fillers in official inspections and their presence is complained.

The migration of the components of the packaging (here, if appropriate, also the sealing liner of the container closure) into the food product is not only generally undesirable, but is also strictly regulated by legislation. Examples of such provisions are EG instructions 1935/2004, 2023/2006, 2002/72/EG, 372/2007, and 2007/19/EG. The maximum amount of migrating components is now allowed to be a maximum of 60 ppm.

The extent of migration that may be observed is measured by means of the method defined, for example, in particular in DIN EN 1186. Such a method also applies in the context of the present invention.

When the closure must comply with the above-mentioned regulations with regard to possible migration of its chemical components, it is important to provide a PVC-free sealing liner for these container closures of the type considered here. Also, the sealing function must be ensured in the case of filling.

Sealing gaskets with barrier function against specific contaminants have been used for small container closures, as described for example in EP 0503124.

However, the requirements for sealing material in container closures having container openings with larger inner diameters (precisely because of the larger amount of material in the seal) are more demanding. For such purposes of use, it is particularly important to combine sufficient flowability of the polymer material with sufficient sealing properties in the closed state when producing the sealing element; here, the currently required tightness against gas penetration or leakage is also included, if necessary in combination with a high-pressure valve effect which prevents the container from exploding when heated and for other reasons an overpressure is produced in the container. In addition, however, it happens that for typical use purposes of containers with larger opening diameters (e.g. cans) it is necessary that the sealing element is usable under sterile conditions (sterilisierung sbedinggungen).

The container closures described in EP 0503124, which are typically designed for filling beer, soft drinks, juices and the like in conventional narrow-necked beverage bottles, must be able to withstand the processing means mentioned there, such as pasteurization and hot filling. Temperatures up to 100 ℃ are used in pasteurization and hot filling. The polymer materials used according to the invention are suitable for pasteurization and hot filling and moreover retain their sealing effect in the necessary range when they are brought into contact with the fat-containing filling.

In all the features described, the seal must also comply with the requirements mentioned above with regard to possible migration of chemical components.

In order to simplify the processing of conventional compounds, extender oils and/or plasticizers are usually added to the compounds. In particular, fluid components such as extender oils and/or plasticizers (preferably white oils) are used here at the application temperature.

It has now been found that such compounds can also be processed, if necessary after a modification of the formulation, to form sealing liners with a larger diameter, but container closures equipped with such sealing liners do not always meet the legislation on migration of chemical components.

Therefore, there is a need for a container closure with a polymer composite based sealing liner, which is preferably not PVC based, and which is suitable for use with containers having a larger opening with an inner diameter of more than 2 cm. In this case, such closures should be pasteurizable and exhibit no interfering migration of the chemical components of the sealed material, and in addition the closures should be used for fat-containing fillers.

Disclosure of Invention

The main object of the present invention is to provide a sealing liner suitable for the production of such container closures, which enables the provision of a container closure with a sealing element based on a polymer compound which is free of PVC and complies with regulations with regard to the migration of packaging components.

Another object of the invention is to define a corresponding container closure.

Furthermore, the invention includes the use of particularly suitable polymer composites to create such container closures.

In order to achieve said object, a sealing gasket for a container closure according to the invention is composed of a composite having the features defined in the embodiments of the invention.

In principle, according to the invention, a container closure is also provided for a container whose opening closed by the container closure has an inner diameter of more than 3 cm. This corresponds to a larger internal diameter than typical beverage bottles closed in a known manner by crown caps, screw caps or the like, as described for example in EP-B10503124.

The invention is particularly suitable for producing comparatively large container closures, i.e. for container openings having an inner diameter of more than 2.5cm up to the opening to be closed having an inner diameter of more than 4 cm.

Such container closures are suitable as rotary lids for bottles, such as juice or milk bottles, storage tanks, jam cans and the like, and especially screw-on lidded cans for fat-containing (especially oil-containing) foods such as sauces, bouquet pastes and the like.

Container closures according to the invention (e.g. in so-called Press-on

) In the form of an enclosure) is also suitable for the packaging of infant and toddler food in a corresponding can.

In the container closure according to the invention, the sealing element is constructed in a similar manner as a gasket on the inner surface of the container closure, as is the case in the known crown caps and screw caps.

In the known bottle closures (crown caps and the like), the sealing element is usually designed as a disk on the inside of the container closure, but as is advantageous according to the invention in larger container closures it can instead be designed as a ring made of a polymer material, which in the closed state of the container rests against the container wall in the region of the opening. Such annular sealing elements are known, but as described, have hitherto only been made of materials containing PVC and a plasticizer, although it is also possible to manufacture them from PU materials.

The method described in US 5763004, which is incorporated in the present description by reference, may be used here.

Detailed Description

Basically, the production method according to the invention assumes that the container-closure blank is made of metal, which is preferably first pretreated on its inside with a suitable primer. In the case of plastic container closures, said preliminary treatment is not required.

Typically, the composition of the primer is based on epoxy phenol. Particularly suitable here are lacquer systems from ACTEGA Rhenania (primer TPE279 with a tie coat TPE 1500) to which the most preferred compounds according to the invention adhere particularly well. However, the tie coat may also be based on polyesters.

Alternatively, suitable primer layers are applied here by lamination, interlining or possibly also by coextrusion.

The polymer material in a heat-flowable form, which should form the seal, is applied to the inside of the thus pre-treated body. Extrusion is particularly suitable here, in which the sealing compound is at a temperature in the range between 100 ℃ and 260 ℃.

When the sealing gasket should be configured as a disc, the pressing may be effected, for example, in the center of the inner surface of the blank. The dose of polymeric material for extrusion is obtained by wiping off a defined amount of the polymeric compound at the upper end of the nozzle.

Next, a disc-shaped sealing element is formed from the extruded and still fluid material by means of a corresponding stamping (analogously to the known SACMI method).

In a modified form, the sealing element can be shaped outside the closure or closure blank by pressing of a suitable polymer material and then incorporated into the closure or blank. The method is also known as shell molding by SACMI for small enclosures.

In particular, the invention relates essentially to container closures made of metal or plastic for containers for containing beverages or foodstuffs, which must be protected against migration of packaging components in a manner complying with legislation. This is for example oily or fat-containing foods, such as prepared foods, but especially oily seasonings and spice pastes, such as curry paste. Extender oils such as white oils, but also plasticizer components, are particularly readily soluble in the oil and grease components of these foods.

In order to ensure the sealing of the container closure, the container closure according to the invention is provided with a sealing liner which meets the requirements described above with regard to its processability on the one hand and its sealing properties on the other hand, and also meets the legal requirements with regard to migration of packaging components.

To achieve this, the material of the sealing liner is selected such that migration of material components into the fat-containing filling is avoided as far as possible, so that no more than 60ppm, preferably significantly less than 60ppm, of migrating components can be detected only in the filling in compliance with applicable european standards.

The material of the sealing liner comprises, as a main component, a polymer composite component, which preferably comprises two different polymer composites. In the present specification, the term "copolymer" has the same meaning as the term "interpolymer", as also described in patent document U.S. Pat. No. 4,16235822. The properties of the main polymer composite component can be suitably modified by doping with other components, for example other polymer composites. It was therefore surprisingly determined that the use of an olefin block copolymer as described in EP-B1714427 as the main component achieves the stated object, in particular when the olefin block copolymer is mixed with a second polymer composite. Suitable as second polymer composite are specific random copolymers, if desired in combination with or instead of HDPE, (co) -PP or other such polymer composite types.

Furthermore, it is preferably provided according to the invention that the material of the sealing gasket contains only very little and particularly preferably no components that are fluid at the application temperature. The application temperature is usually the same as the ambient temperature, i.e. in the range of the normal ambient temperature outdoors or in a heated room. Thus, according to the invention, only a small amount or preferably no fluid extender oil, such as in particular white oil, is added to the material of the sealing liner.

In a preferred embodiment, the material comprises not more than 10%, preferably not more than 7%, particularly preferably not more than 4% and particularly preferably not more than 1% of a lubricant, which, in the migration test, is limitedly transferred into the fat-containing filler within 10 days at 40 ℃.

It is now most preferred that the material not include at all the components that are fluid at the application temperature within the analytical determination limits given at the time of filing of the application.

It is furthermore preferred that the material of the sealing liner does not comprise a plasticizer.

Since, in particular, when the container closure diameter exceeds 3cm and when the material is constructed as described in EP 0503124 on the basis of styrene-containing block copolymers with elastomer segments, compounds of such sealing gaskets, which may be free of extenders, are difficult to process, it is preferred according to the invention to use materials which do not comprise such polymer compounds.

It is therefore preferred that the material forming the gasket comprises neither the fluid extending oil nor the plasticizer, nor the styrene-containing block copolymer having elastomeric segments. Alternatively, it is preferred that the polymer material forming the main component of the sealing liner is based on a specific polyalkylene which can also be processed without extender oils or the like to form sealing liners for container closures having a diameter of more than 3 cm.

This shows that, on the one hand, block copolymers which comprise firstly polyethylene units and which are furthermore composed of olefin monomers, the olefins being selected from propylene, butene, hexene and, in particular, octene, are particularly well suited for this.

Such copolymers can be produced in a targeted manner with the desired physical properties by means of metallocene catalysts.

Suitable polymer composites are described in EP-B10714427. It is stated therein that such polymer compounds can also be processed as sealing gaskets themselves, wherein no additives are to be added. In contrast, the present invention is based in particular on the following statements: such polymer compounds can be processed into improved sealing gaskets when additives according to the invention are added. The problem of migration of material components in the case of fat-containing fillers is not mentioned here.

On the other hand, random copolymers are particularly well suited as components of composites which are composed firstly of ethylene and furthermore of at least one C₃-C₂₀Suitable random polymer complexes are described, for example, in US 6, 235, 822.

It is evident here that further formulation variants are possible according to the invention in which block copolymers in the range from 20% to 100%, random copolymers in the range from 0% to 80%, and, as additional components, other polyolefins, in particular styrene-ethylene-butylene-styrene (SEBS), HDPE or (co) PP, are present in a content of up to 25%.

According to the invention, the formulation may comprise: ethylene-octene block copolymers, such as Infuse D9007 in the range of 37% -41%; ethylene-octene random copolymers, such as Engage 8402 in the range of 58% to 62%; antioxidants, such as Irganox 1010 in the range of 0.1% to 0.3%; stabilizers, such as Irgafos168 in the range of 0.0% to 0.2%; lubricants, such as erucamide in the range of 0.2% to 0.4%; lubricants, for example, oleamide in the range of 0.2% to 0.4%.

Exemplary formulations for pasteurization and hot fill include:

according to the invention, the material generally has a shore a hardness of 45 to 95 with a shore D hardness of about 25 and in particular a shore a hardness of about 85 according to the formulation. The polymer composite has a compression set (DVR) (similarly determined according to compression set test ASTM D395-97, method B) of between 50% and 80%.

According to the invention, starting from a hot fill of up to 10 minutes and at least 60 ℃ for at least 1 minute, the polymer material can withstand a hot fill of up to 100 ℃ within 60 minutes. Hot filling can be achieved in 5 ℃ steps up to 100 ℃ in 60 minutes starting from 60 ℃.

Apparent shear viscosity was 100s at 185 deg.C^-1<100Pa.s and at 500s^-1<50 Pa.s. This was measured by means of a two-channel rheometer Propoise P9 with a nozzle diameter of 0.5 mm.

Optionally, a coating, preferably an inorganic coating, may also be added to the formulation of the composite in order to preclude migration of the coating. It is apparent that further additives such as waxes, silicones and, in particular, blowing agents can be added to the polymer composite, for example, to improve processing and use properties.

In addition, polymer composites typically exhibit a compression set (DVR) of 30% to 90% at 70 ℃ in a compression set test similar to ASTM D395-97 method B. DVR is a higher value for sterilized products, up to 90%. For pasteurizable (but not sterilizable) products, the DVR may be a smaller number, up to about 80%. For compounds with thermoplastic vulcanizates (TPV materials), the lower limit of DVR can be a minimum of 30%; for other materials, the DVR range is preferably at least 50%.

The material can also be processed, for example, with the method described in our parallel international patent application (patent name "method for manufacturing container closures") into a sealing element for correspondingly large container closures. It is thus possible for example for a lug cap with a diameter of more than 60mm to be provided with sealing gaskets which comply with the regulations of EC regulations 1935/2004, 2023/2006, 2002/72/EG, 372/2007 and 2007/19/EC for the first time.

In connection with the above regulations, it is necessary to carry out migration tests on container closures according to the invention in the manner and method as described in DIN EN 1186. Therefore, the description of the method is omitted in the context of the present application; the test is incorporated into the disclosure of the present application by reference to DIN EN 1186.

According to the invention, it is achieved by using the polymer material that not only can the sealing gasket thus produced be produced without difficulty, but also the sealing gasket has the sealing properties described at the outset. Furthermore, such container closures are pasteurizable and meet european regulations relating to the migration of polymeric material components into beverages or foodstuffs contained in containers closed in the manner according to the invention, in particular into fat-containing fillings.

In this connection, the provisions of the european directive mentioned are in particular in combination with the test criteria of DIN EN1186 to form suitable selection criteria for polymeric materials which can be obtained from a large number of principally conceivable compounds by avoiding components which are fluid at the application temperature and by subsequent testing.

As can be seen from the above description, the embodiments of the present invention cover, but are not limited to, the following technical solutions:

scheme 1. a polymer composite for a sealing gasket of a container closure, in particular for a fat-containing filling, said polymer composite being configured such that migration of components of said composite into the filling is reduced, characterized in that the shore a hardness of said polymer composite is between 45 and 95 and said polymer composite exhibits a compression set (DVR) of 30% to 90% at 70 ℃ in a compression set test similar to ASTM D395-97 method B.

Scheme 2. the composite according to scheme 1, characterized in that it comprises between 20% and 100% of at least one block copolymer, wherein said block copolymer is preferably at least one C₃-C₂₀- α -interpolymers of olefins with ethylene or, if desired, in combination with other unsaturated monomers, C₃-C₂₀- α -copolymers of olefins with ethylene.

Scheme 3. the composite of scheme 2, wherein the block copolymer has 0.85g/cm³To 01.1g/cm³And preferably has a melt index (MFI) of from 0.01g/10min to 1000g/10min, in particular an MFI of from 1g/10min to 100g/10min, at 190 ℃ in an amount of 5 kg.

Scheme 4. the composite according to one of schemes 1 to 3, characterized in that the block copolymer is formed from polyethylene and an olefin, in particular selected from propylene, butene, hexene and octene, and particularly preferably octene.

Scheme 5. the compound according to scheme 1, 2, 3 or 4, characterized in that it comprises between 0% and 80% of at least one random copolymer, wherein said random copolymer is preferably with C₃-C₂₀- α -Linear interpolymer of olefin and ethylene or C₃-C₂₀α -branched interpolymers of olefins with ethylene.

Scheme 6. the composite of scheme 5, wherein the random copolymer has 0.85g/cm³To 1.1g/cm³And preferably has a melt index (MFI) of from 0.15g/10min to 100g/10 min.

Scheme 7. the composite according to one of the schemes 1 to 6, characterized in that the random copolymer comprises two olefins, in particular chosen from ethylene, propylene, butene, hexene and octene, and in particular comprising ethylene and octene.

Scheme 8. the compound of scheme 7, wherein at least one copolymer is polymerized by metallocene catalysis.

Scheme 9. the compound according to scheme 1, wherein the compound comprises between 20% and 100% of at least one olefin copolymer, which olefin copolymer is not a block copolymer.

Scheme 10. the compound according to one of the schemes 1 to 9, characterized in that it comprises from 0% to 25% of a polyolefin, in particular HDPE and/or (co) PP and/or SEBS.

Scheme 11. the composite according to one of schemes 1 to 10, characterized in that the composite has a shore a hardness of 65 to 90, and particularly preferably a shore a hardness of about 85, the shore D hardness being about 25.

Scheme 12. the composite according to one of the schemes 1 to 11, characterized in that the compression set of the composite at 70 ℃ is between 55% and 75% and in particular about 70%.

Scheme 13. the compound according to one of the schemes 1 to 12, characterized in that it comprises additives such as waxes, silicones and in particular blowing agents.

Scheme 14. the composite of any of schemes 1 to 13, wherein the container closure is a lug cap, a compression screw cap, a slip cap, a crown cap, or a flip top metal closure.

Scheme 15. the composite of one of the schemes 1 to 14, wherein the material composition of the sealing liner is selected such that the closure meets the regulations of act (EG) 1935/2004.

Scheme 16. the composite of any of schemes 1-15, wherein the material composition of the sealing liner is selected such that the closure meets the regulations of act (EG) 2023/2006.

Scheme 17. the composite of any of schemes 1-16, wherein the material composition of the sealing liner is selected such that the closure meets the criteria 2002/72/EG.

Scheme 18. the composite of one of the schemes 1 to 17, wherein the material composition of the sealing liner is selected such that the closure meets the regulations of act (EG) 372/2007.

Scheme 19. the composite of any of schemes 1-18, wherein the material composition of the sealing liner is selected such that the closure meets the criteria of 2007/19/EC.

Version 20. the compound according to one of the preceding versions, characterized in that the sealing liner can be subjected to sterilization at a temperature of 95 ℃, in particular 121 ℃ and particularly preferably up to 132 ℃, in contact with a fat-containing filler.

Scheme 21. the compound of one of schemes 1 to 19, having the form of thermoplastic particles.

Scheme 22. use of a polymeric material to make a sealing gasket for use in a container closure containing a fat-containing filler, wherein migration of a component of the polymeric material into the filler complies with the provisions of act (EG)1935/2005, also preferably act (EG)2023/2006, especially act (EG)372/2007, and particularly preferred guidelines 2002/72/EG and 2007/19/EG.

Scheme 23. a sealing gasket comprising the polymer composite according to one of schemes 1 to 20.

Scheme 24. a container closure having a sealing liner comprising the polymer composite according to one of schemes 1 to 20.

Claims

1. A container closure for a container having an opening with an inner diameter of more than 2cm, which opening is to be closed by the container closure comprising a polymer compound-based sealing element which is arranged in the container closure such that the sealing element contacts the opening of the container in a sealing manner in the closed state,

wherein the polymer composite has a Shore A hardness of between 45 and 95, and

the material formed into the sealing element is not based on styrene-containing block copolymers with elastomeric segments,

the polymer composite is free of PVC and comprises two different polymers, one of these polymers being a block copolymer comprising polyethylene units and consisting of olefin monomers selected from the group consisting of propylene, butene, hexene and octene, and

the other of these polymers is a random copolymer consisting of a linear or branched interpolymer of ethylene and at least one C₃-C₂₀- α -olefin.

2. A container closure as in claim 1 wherein said polymer composite comprises:

-in the range of 20% to 100% of said block copolymer comprising polyethylene units and consisting of an olefin monomer selected from propylene, butene, hexene and octene;

-in the range of 0% to 80% of said random copolymer consisting of a linear or branched interpolymer consisting of ethylene and at least one C₃-C₂₀- α -olefin composition, and

-from 0% to 25% of other polyolefins.

3. A container closure as in claim 2 wherein said polymer composite comprises no more than 10% of a lubricant that is fluid at application temperatures.

4. A container closure as in claim 3 wherein said polymer composite comprises no more than 7% of a lubricant that is fluid at application temperature.

5. A container closure as in claim 4 wherein said polymer composite comprises no more than 4% of a lubricant that is fluid at application temperatures.

6. A container closure as in claim 5 wherein said polymer composite comprises no more than 1% of a lubricant that is fluid at application temperatures.

7. A container closure according to any of claims 1 to 6, wherein said block copolymer is produced by metallocene catalysis.

8. A container closure as in any of claims 1 to 6 wherein said polymer composite has a Shore A hardness in the range of 65 to 90.

9. A container closure as in any of claims 1 to 6 wherein said polymer composite is configured such that said sealing element is usable under pasteurization conditions up to 100 ℃.

10. A container closure as in any of claims 1 to 6 wherein said polymer composite is configured such that said sealing element is usable under sterilization conditions of 121 ℃.

11. A container closure as in any of claims 1 to 6 wherein said polymer composite is configured such that said sealing element is usable under sterilization conditions of 132 ℃.

12. A container closure as in any of claims 1 to 6 wherein said polymer compound having a flowability is applied onto the inside of said container closure through a nozzle.

13. A container closure as in any of claims 1 to 6 wherein said polymer composite further comprises an additional polyolefin selected from HDPE and co-PP and styrene-ethylene-butylene-styrene.