HK1090077B - Erucamide-free closure and liner compositions - Google Patents

Description

Erucamide-free closure and gasket compositions

Technical Field

The present invention relates to compositions for producing closures and closure liners, and more particularly to erucamide-free compositions.

Background

It is known to produce container closures and closure sealants using polymers with erucamide as a slip agent. However, erucamides are ethylenically-unsaturated amides that react with ozone used in sterilization, thereby producing aldehyde off-flavors that adversely affect beverage products such as carbonated water and soft drinks. However, the use of saturated amides (e.g., behenamide) as slip aids tends to be less effective when avoiding the off-taste problem because it is believed that they migrate relatively slowly to the surface of the matrix polymer and are not effective in providing a low friction surface.

As noted in world patent WO 0236672a1 to Alphagary Corporation, it should be noted that common closure sealants for beverage or food containers utilize lubricants such as erucamide and oleamide, each of which is conjugated. Because these lubricants are conjugated, they undergo photochemical decomposition and oxidative decomposition reactions. In other words, oxidative decomposition of erucamide by ozone sterilization can produce flavor-damaging contaminants other than aldehydes, such as ketones. Bottled water products, such as mineral water and spring water, are often sterilized using ozone sterilization. The U.S. food and drug administration requires ozone sterilization of bottled water products produced and sold in the united states. Thus, there is a need for a closure sealant lubricant that is resistant to oxidative degradation by ozone sterilization. In addition, there is a need for a closure sealant lubricant that is resistant to photochemical and thermal decomposition. Exposure to uv light can also cause photochemical degradation of erucamide to produce flavor-damaging chemicals, and this negative effect can be tested using a number of industry standard assays. Erucamide degradation problems also occur during transportation or storage in hot climates due to high temperatures.

Thus, there is a need for a new erucamide-free composition for use in the production of container closures and closure sealants.

Disclosure of Invention

In order to overcome the problems identified above, the present invention provides a composition suitable for container closures and closure sealants, the composition comprising: (A) a matrix polymer, copolymer or blend of polymers and/or copolymers that is substantially free of erucamide, that is substantially free of unsaturated amide; (B) a siloxane having an average molecular weight of not less than 40,000 and in an amount of not less than 0.01 parts but not more than 10 parts based on 100 parts of the one or more base polymers; and (C) a slip aid comprising a saturated amide, oxidized polyethylene or mixtures thereof; the amount of such slip aid is not less than 0.01 parts but not more than 8 parts based on 100 parts of the base polymer or polymers.

The present invention contemplates the use of polymers, copolymers and blends thereof which are generally known as matrix polymers for closures and sealants.

The present invention also relates to lubricant/slip aid compositions for use in container closures and closure sealants. Representative slip aid compositions contain: silicone lubricants (e.g., siloxanes, organosiloxanes) having an average molecular weight of greater than 40000 are present in an amount of 0.01 to 10 parts based on 100 parts of one or more matrix polymers and a slip aid comprising a saturated amide, oxidized polyethylene or a mixture thereof.

Other advantages and features will be described in more detail below.

Detailed Description

As briefly indicated above, representative compositions comprise a matrix polymer; a silicone lubricant; and a slip aid comprising a saturated amide, oxidized polyethylene, or a mixture thereof.

Such matrix polymers, copolymers or blends thereof may be selected from those commonly known for use in the production of containers, container closures or closure sealants. These include, for example, thermoplastic polymers, such as polyethylene or copolymers of ethylene with other lower alkenes, polypropylene, thermoplastic rubbers, ethylene propylene copolymers, acid modified ethylene propylene copolymers, styrene butadiene rubbers, carboxylated styrene butadiene copolymers, polyisoprene, styrene isoprene styrene block copolymers, styrene butadiene styrene block copolymers, styrene ethylene butylene styrene block copolymers, polystyrene block polyethylene/propylene copolymers, polystyrene block polyethylene propylene polystyrene copolymers, polystyrene block polyethylene ethylene propylene styrene copolymers polystyrene, ethylene vinyl acetate copolymers and terpolymers, ethylene acrylate copolymers and terpolymers, ethylene vinyl alcohol copolymers, butyl rubber, ethylene acid copolymers and polyvinyl chloride polymers.

The composition of the present invention should be substantially free of erucamide, which is substantially free of unsaturated amides. In other words, the iodine value of the amide in such compositions should not be higher than 10, more preferably not higher than 5. Iodine value is a measure of the unsaturation of alkyl groups, which can be measured using the Wjis method, such as ASTM D2075-92.

Typical closure sealing gasket embodiments are described, for example, in US 5104710, EP 0478109, EP 0599356, EP 0488491 and 0646158. The sealing liner may be used in the closure by any known method, such as for example the methods described in US 4518336, EP 2073385 and US 4277431.

Typical closure embodiments are described, for example, in US 5045594, US 5186991, US 6399170, WO 0162837, EP 73334 and US 4462502.

The addition of silicones to closure and closure sealant compositions is not new, examples of which are seen for example in EP 129309. However, they are used in combination with one or more unsaturated amides to provide the ability to mitigate removal torque.

In another embodiment of the present invention, at least one siloxane may be used. For example, japanese patent application No.2000038495 describes high molecular weight silicones as slip aids in cap liners. However, the present inventors believe that the use of silicones alone is not effective in providing sufficient removal torque reduction and there is a polymer scuffing problem.

In another representative embodiment of the present invention, polysiloxanes may be used as processing aids. See for example EP 0331485. A preferred silicone lubricant is a silicone available from Dow Coming under the trade name DC 200 FLUID. Preferably, such silicones have a viscosity of greater than 50,000 cst. A particularly preferred material is also available from Dow Coming under the trade name Sipowder Resin Modifiers and MB Master Batches, e.g., MB 50-320 and MB 50-002A. Such silicones are generally used in amounts of 0.01 to 10 parts by weight, based on 100 parts total polymer, preferably in the range of 0.01 to 5 parts by weight, based on 100 parts total polymer.

Slip aids are used to reduce the force required to remove the closure from the bottle or package. These slip aids are found in the literature examples using unsaturated amides, see for example JP2002068282, US 5929128, JP 02191166. However, the present inventors believe that the use of saturated amides in container closures or closure sealants is novel. Saturated amides contemplated as suitable for use in the present invention include behenamide, arachidamide, stearamide, palmitamide, myristamide and lauramide. These saturated amides are commercially available from Croda Universal. The term "saturated" as used herein shall mean compositions wherein the iodine value is not higher than 10, more preferably not higher than 5.

Secondary saturated bis-amides are also considered slip aids suitable for use in the present invention. For example, ethylene bis-stearamide is a product of CRODA universal available on the market under the trade name CRODA EBS. The preferred amide for use in the present invention is stearamide.

Oxidized polyethylenes, with or without saturated amides, are also considered suitable slip aids for use in the present invention. These oxidized polyethylenes are commercially available from Honeywell under the trade name A-C, a particularly preferred version being referred to or designated as "A-C629A". Typical ranges for both types of slip aids are 0.01 to 8 parts based on 100 parts of the base polymer or polymers.

Optional components for use in the composition and method of the invention include pigments, antioxidants, stabilizers, uv absorbers, molecular sieves, hydrocarbon oils, phthalate plasticizers, peroxide soybean oil, blowing agents, acrylic processing aids, fillers, and nanocomposites. In addition, active fill components such as oxygen scavengers, aldehyde scavengers, antimicrobials, and flavor enhancers may be included.

Representative compositions of the invention may be formed into beverage or food containers, closures or closure sealants, such as lidding sheets, for example, by molding.

The present invention also provides slip aid compositions. Representative slip aid compositions for container closures and closure sealants contain: polysiloxanes, such as siloxanes, organosiloxanes, such as poly (dimethyl) siloxanes having an average molecular weight of not less than 40,000, in an amount of not less than 0.01 parts, but not more than 10 parts, based on 100 parts of one or more of the base polymers; and a slip aid comprising a saturated amide, oxidized polyethylene, or a mixture thereof; the amount of said slip aid is not less than 0.01 parts but not more than 8 parts based on 100 parts of one or more of said base polymers.

The foregoing detailed description and examples have been provided for the purpose of illustration only and are not intended to limit the scope of the invention. In these examples, the following abbreviations are used:

EVA-1 ethylene-vinyl acetate copolymer, 14% VA

EVA-2 ethylene-vinyl acetate copolymer, 9% VA

EP ethylene-propylene copolymer

ER Crodamide^TM ER

SR Crodamide^TM SR

EBS Crodamide^TM EBS

Si1 Dow Coming^TM200fluid，60000cst

Si2 Dow Coming^TM200fluid，100000cst

Si3 Dow Coming^TMMB50-320

Si4 Dow Corning^TMMB50-002

AO antioxidant

BLUE pigments

Oxp oxidized polyethylene

UV1 Tinuvin^TM 622

UV2 UVinul^TM3030

Example 1

The compositions of table 1 below were blended and extruded into films and die cut into 1 inch disks. These disks were then inserted into 28mm polypropylene bottle caps intended for carbonated soft drinks. A 20 ounce force was then applied to the caps. PET bottles were filled with water using commercial machinery. These bottles were stored at room temperature for less than a week but longer than 24 hours, after which the force required to open the cap was measured and no tearing, scratching or stringing of the liner was observed.

TABLE 1

	A	B	C	D	E	F	G
								EVA-1 EPAOBLUEEREBSSSROXPSi 1Si2Si3 Torque, in-lbs	90100.10.80000000＞23.6100％	90100.10.8100000010.610％	90100.10.801.500000＞24.270％	90100.10.8001.500002080％	90100.10.8000100020.640％	90100.10.8000010016.7100％	9010.1.8000000213.2100％

As previously indicated, none of the lubricants or slip aids alone provide the same degree of performance as erucamide. Stringing and/or scuffing of the sealing liner is believed to be caused by tearing of the sealing liner from the bottle surface. This is considered unacceptable in the food and beverage industry because it can cause contamination of the packaging. The lack of adequate lubrication/slip properties of the gasket surface can make it even more severe.

Example 2

The following compositions were applied to caps and tested according to the method described in example 1 above, and the results are shown in table 2 below.

TABLE 2

	A	B	C
				EVA-1EPAOBLUESi3Si2SROXP Torque-removing IN-LB. stringing/galling	9010.1.83001.513.60％	9010.1.8301010.30％	9010.1.801.51.512.014％

This data shows that the use of a mixture of silicone and ethylenically saturated amide and/or oxidized polyethylene, when combined, provides the same performance as erucamide.

Example 3

In another embodiment, the compositions identified in Table 3 are extrusion blended and pelletized. The pellets are melted using another extruder and applied to the bottle caps using well known methods (see for example EP 207385).

The resulting lined caps were allowed to age at room temperature for a minimum of 1 week and tested (to test the removal torque required to remove the cap from the PET bottle). The caps were mounted on 500ml pet bottles and the bottles were carbonated using a commercially available machine. The capped bottles were stored at both cold and room temperature and their removal torque was measured after a certain period of storage. The results are shown in table 3 below, column a representing an erucamide-free liner formulation and column B representing an erucamide-containing formulation, expressed in parts Per Hundred Resin (PHR).

TABLE 3

Sealing gasket formulation	A	B
			EVA-2AOBLUE erucamide Si4Si2SROXP removal Torque in-lbs.24 hours @4 deg.C 1 week @23 deg.C	1000.10.800.81.30.30.813.814.311.1	1000.10.81.0000015.316.211.0

This data shows that the use of a mixture of silicone, ethylenically unsaturated amide and oxidized polyethylene, when combined, does provide the same or better performance as the erucamide containing bottle cap closure formulations.

Example 4

In another embodiment, a composition similar to that described above is extrusion blended and pelletized. The pellets were then melted using another extruder from which the melted pellets were transferred directly to individual bottle caps and immediately compression molded.

The resulting lined caps were aged at room temperature for a minimum of 1 week and tested. Then 20 ounces of force was applied to this lid. Water was filled into PET bottles using commercial machinery. This bottle was stored at 40F for not less than 1 week, but longer than 24 hours. After this time, a test was performed to measure the force required to remove the cap without any tearing, scratching or stringing of the liner.

Compositions containing a siloxane in combination with an ethylenically unsaturated amide and/or an oxidized polyethylene slip aid give removal torques comparable to compositions containing erucamide. Its identifying of the adherent filaments is commercially acceptable using industry standards. However, compositions using only siloxanes without unsaturated amides and/or oxidized polyethylene give high removal torque and stringing and are unacceptable.

Example 5

In another example, the compositions in table 4 were extrusion blended and granulated. The pellets were then extruded into a tape having a thickness of about 17 mils. One inch diameter disks were punched from this tape and placed in a clean glass jar. The jar was stored for four days at 115 deg.F, removed and held for one day at 68 deg.F. Three disks were removed from the glass jar, two inserted into twenty ounce PET bottles and one inserted into a commercially available 28mm bottle cap. These bottles were filled with distilled water, capped, and placed at 115F for six days and then at 68F for storage. The water samples were placed on a training sensory panel and evaluated using a fragrance test method of accepted industry standards. The formulation without erucamide had significantly lower intensity of flavor and odor than the erucamide control sample.

TABLE 4

	A	B
			EVA-1EPAOBLUE erucamide Si3Si2SROXP	9010.1.80.81.338	9010.1.810000

Example 6

In another sensory example, the compositions of table 5 were extrusion blended and pelletized prior to extrusion into tapes. Samples of the mineral water gasket compound currently in use on the market were extruded into tapes and used as control samples. A plurality of discs were die cut from the tape and inserted into clear commercial 28-mm plastic caps. A265 ml clear glass bottle was filled with water, the headspace of which was 5% by volume and manually closed. The bottle was then placed in a sun tester under the following conditions:

xenon lamp Nxe-1500A

A quartz filter: 290mn

Distance between the filter and the bottle cap: 17cm

Exposure time: for 42 hours.

The water samples were then evaluated using a training plate using the triangle test method.

TABLE 5

	A
		Si4	8
Si2	1.3
		SR	0.3
OXP	0.8
		EVA-1	100
AO	0.1
		BLUE	0.8
UV1	0.3
		UV2	0.25
Sensory results compared to commercial control samples
		Effectiveness of	96％
Difference in	6
		Preference is given to	A
The difference scale 1-13, 1 is very small and 13 is very strong

Sensory results after exposure to uv light showed that the erucamide-free compound was significantly better than the commercial control sample.

The removal torque performance achieved with the compositions of the invention when compounded with the silicone and ethylenically unsaturated amide and/or oxidized polyethylene mixture is the same as that of erucamide.

The foregoing detailed description and examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Claims (20)

1. A composition comprising:

(A) a matrix polymer, copolymer or blend thereof, which is free of erucamide, which is free of unsaturated amide, and which is processed to provide a container, container closure or closure sealant, said matrix polymer, copolymer or blend thereof being selected from the group consisting of polyethylene or copolymers of ethylene and other lower alkenes, polypropylene, thermoplastic rubbers, poly (ethylene propylene) copolymers, acid modified ethylene propylene copolymers, styrene butadiene rubbers, carboxylated styrene butadiene copolymers, polyisoprene, styrene isoprene styrene block copolymers, styrene butadiene styrene block copolymers, styrene ethylene butylene styrene block copolymers, polystyrene block polyethylene/propylene copolymers, ethylene vinyl acetate copolymers or terpolymers, ethylene acrylate copolymers or terpolymers, polyethylene vinyl acetate copolymers or copolymers, polyethylene vinyl acetate copolymers, polyethylene glycol, A thermoplastic polymer of ethylene vinyl alcohol copolymer, butyl rubber and polyvinyl chloride polymer,

(B) a lubricant containing an organopolysiloxane having an average molecular weight of not less than 40,000 in an amount of not less than 0.01 parts by weight but not more than 10 parts by weight based on 100 parts by weight of the matrix polymer, copolymer or blend thereof constituting the component (a); and the viscosity of the organopolysiloxane is at least 50,000cst, an

(C) A slip aid comprising a saturated amide and oxidized polyethylene, in said composition, in an amount of not less than 0.01 parts by weight but not more than 8 parts by weight based on 100 parts by weight of said component (a), said amide having an iodine value of not more than 5 according to ASTM D2075-92;

the compositions, when used in a container, container closure or closure sealant, provide lower off-taste compared to compositions containing unsaturated amides while maintaining slip aid efficiency.

2. The composition of claim 1 comprising at least two of said thermoplastic polymers or copolymers.

3. The composition of claim 1 wherein said matrix polymer, copolymer or blend thereof comprises an ethylene vinyl acetate copolymer in an amount not less than 5 parts by weight but not greater than 100 parts by weight based on 100 parts by weight of said component (a).

4. The composition of claim 1 wherein the matrix polymer, copolymer or blend thereof comprises polyethylene, polypropylene or blends thereof.

5. The composition of claim 4 wherein the matrix polymer, copolymer or blend thereof comprises a copolymer of polyethylene and polypropylene.

6. The composition of claim 1 wherein said organopolysiloxane is poly (dimethyl) siloxane.

7. The composition of claim 1 wherein the saturated amide is selected from the group consisting of behenamide, stearamide, arachidamide, palmitamide, myristamide, lauramide and ethylene bis-stearamide.

8. The composition of claim 7 wherein said saturated amide is stearamide.

9. The composition of claim 7 wherein said saturated amide is behenamide.

10. The composition of claim 1 molded into a beverage container.

11. The composition of claim 1 molded into a beverage container closure.

12. The composition of claim 11 wherein said beverage container closure is a plastic cap.

13. The composition of claim 1 molded into a gasket for a closure.

14. The composition of claim 1 wherein the matrix polymer comprises an ethylene vinyl acetate copolymer and further comprises a poly (ethylene propylene) copolymer.

15. The composition of claim 1 wherein said ethylene vinyl acetate copolymer or terpolymer and said poly (ethylene propylene) copolymer comprise 100% of said matrix polymer.

16. The composition of claim 14 wherein said saturated amide is stearamide.

17. The composition of claim 16 wherein said organopolysiloxane is poly (dimethyl) siloxane.

18. The composition of claim 1 wherein said matrix polymer comprises a poly (vinyl chloride) polymer.

19. The composition of claim 18 wherein said poly (vinyl chloride) polymer comprises 100% of said matrix polymer.

20. The composition of claim 1 wherein the matrix polymer comprises polyethylene, polypropylene, or mixtures thereof, and the matrix polymer further comprises a styrene ethylene butylene styrene block copolymer.