WO2008010818A1

WO2008010818A1 - Material compositions and designs of oxygen scavenging closure for packaging

Info

Publication number: WO2008010818A1
Application number: PCT/US2006/032887
Authority: WO
Inventors: Dexi Weng
Original assignee: Dexi Weng
Priority date: 2005-09-19
Filing date: 2006-08-21
Publication date: 2008-01-24

Abstract

A molded closure for a liquid container comprising a thermoplastic elastomer and another polymer compound having oxygen scavenging capability and oxygen scavenging compositions are claimed. The molded closure is especially suitable for use as a synthetic wine cork in a wine bottle or container. The molded closure does not allow passage of oxygen into the container or bottle. It absorbs oxygen from the contents of the container. The molded closure can be removed from the bottle using a corkscrew without significant expansion, crumbling or disintegration.

Description

Material Compositions and Designs of Oxygen Scavenging Closure for Packaging

The present invention relates to formed, molded or extruded closures for containers and to compositions and methods for making such closures. In one aspect, the present invention relates to a particular design for making corks for bottles, especially wine bottles.

[1]

Today people are more and more concerned about the quality of the foods, beverage they consume. People desire more nutrition, freshness in foods and beverages. However, foods and beverages are easily oxidized. Once foods are oxidized, their nutritional values and tastes deteriorate drastically, even to the point when the foods become inedible or toxic. The wine industry knows the fact that the wine contained in a container is susceptible for oxidation from oxygen molecules.

Oxygen comes from outside of the container due to the imperfection of the closure, or cork or stopper. Oxygen can also exist as dissolved entity in the liquid, for example, wine itself. There have been several methods to slow down or control wine oxidation process. One method is to add in wine some oxygen scavenging compound, which reacts with oxygen, thus competes with the oxidation reaction of oxygen with wine. Another method is to use a natural cork to seal a wine bottle. Typically wine brewers use the combination of the two above-said methods. Although the combination has been successful to some extent commercially, there are several disadvantages for this combination. Natural corks are not uniform in terms of color, shrinkage or expansion, and seal formation. The crumble easily. These undesirable properties are not suitable for mass production and hence increase cost of wine significantly. Natural corks may also impart odor to wine, causing wine to be rejected by consumers. Some reported that nearly 10 to 15% of bottled wine is discarded annually because of unpredictable contamination from the natural cork. Natural corks are also treated with chemicals to eliminate mold or other organisms. A serious side effect is the formation of TCA (Trichloro anisole). TCA, even in ppb levels in wine, causes rejection of wine by consumers due to human's high sensitivity to trace amount of TCA. Furthermore, the availability of natural corks is rapidly becoming a problem since it takes quite a long time (in several decades) for the special oak trees to grow to the point when the barks are harvested. Several alternatives to the natural cork have been attempted. Noticeably successful ones are exemplified as described by US patents US5,480,915 and US5,904,965. These patents describe methods of replacing natural corks with synthetic ones, formed by either injection molding or extrusion. These synthetic corks, however, do not address the oxidation problem occurs inside the wine. Some also reported that these synthetic corks permeate more oxygen and faster than the natural corks.

To control or slow down oxidation that occurs inside wine itself, breweries traditionally have attempted to add into wine some chemical compounds which react with oxygen and hence protect wine from extensive oxidation, as described earlier in this patent These compounds are called oxygen scavengers. Sulfites are examples. Sulfites are a group of molecules that are effective when added to the wine directly. However, people are starting to notice the adverse effects of sulfites to human health. Some people develop severe asthma after consuming beverages or foods treated with sulfites or related products. The Food and Drug Administration

(FDA) of US requires the labeling of the presence of sulfites to warn consumers of the risks of consuming sulfites containing wines. This is a serious disadvantage for the wine breweries, whole sellers and retailers. The synthetic corks, as described in US patents US 5,480,915 and US5,904,965, do not absorb oxygen from the inside of the wine bottle. Therefore the performance of these synthetic corks is only as equal to or maybe slightly better than the natural cork in some aspects. [2]

Disclosure of Invention

As described in the background art section, we need to protect wine from oxidation for shelf life, freshness and nutrition. The natural corks are becoming scarce as supplies are limited and oak trees take long time to be harvested. Natural corks break easily and often impart undesirable odor to wine. The current synthetic corks solved some problems associated with natural corks such as odor and breakage. The current synthetic corks do not slow down oxygen permeation as efficiently as natural corks. The shelf life of a typical wine is still very limited with the current synthetic corks.

[31

The solution for the above-mentioned problems is the oxygen scavenging polymer cork of this invention. This invention describes a cork made of polymeric materials. One portion of the materials also absorbs, or scavenges oxygen. The oxygen scavenging portion is preferably encased inside a polymer skin. The formed closure provides mechanical seal and actively scavenges oxygen at the same time to protect wine. [4]

The polymer cork of this invention does not crumble as the natural cork. The polymer cork also improves over the current synthetic cork in that it possesses oxygen scavenging capabilities. Thus the polymer cork of this invention improves over both the natural cork and the current synthetic cork to protect the packaged wine. This invention can be extended to package other types of contents, which is obvious to those experienced in the art. [5]

Figure 1. Photograph of a prototype of a wine cork, the top piece is the whole cork, while the bottom piece is the half piece cut out of a whole piece along its axis. [6]

In this invention, there is provided a formed closure for a liquid container thus it can function as a suitable replacement for a natural cork or a synthetic cork described elsewhere in earlier inventions. It is also the intent of this invention to provide the breweries to diminish or even eliminate the amounts of oxygen scavengers added in the packaged wine. Hereby the health aspect of consuming wines is greatly improved. This invention is substantially different from the inventions such as described in US5,480,915 and US5,904,965, wherein it is specifically claimed that the closures do not have oxygen scavenging capability.

In another aspect of the invention, the closure can preferably be formed through a process of double injection molding or insert molding. In the double injection molding process, or variably called co-injection molding process, the core and the skin compositions are injected to the same mold cavity simultaneously or with a slight time delay of one from the other. In the insert molding process, the core is formed first and then inserted into another cavity whereby the skin layer is injection molded over the core to encase it The core layer provides oxygen scavenging capability of the closure while the skin layer separates the packaged beverage from the core of the closure. There may be a possibility of migration of the scavenging reaction by-product from the core to the packaged liquid if no skin layer is present The skin layer acts as a barrier for this migration. The skin layer also functions as a lubricated surface for easy insertion and removal of the closure.

In a preferred embodiment, the core is made of an oxygen scavenging composition by injection molding or extruding the composition or compound and then cutting the extrudate into appropriate length. The molded or extruded pieces are then inserted in another mold or cavity for insert injection molding to form a skin layer. The skin layer consists preferably of a soft polymer material such as a thermoplastic elastomer (TPE), or a regular plastic material, foaraable or non-foamable, or a crosslinkable polymer material can also be used. In still another embodiment, the core layer and the skin layer are injection molded into the same cavity through a process called co-injection molding or double injection molding process. It is also possible to injection mold the core and skin at a slight time delay. It is obvious to the experienced in the art there will be other operations to make corks with a skin layer encasing a core. [7]

Compositions of the core:

The core of the closure is made of compounds having oxygen scavenging capabilities. Examples of the preferred compositions are provided herein.

Example 1:

50 phr of SEBS polymer Taipol 3151 and SOphr of SBS polymer Taipol

3202, both from Taiwan Synthetic Rubber Company (TSRC), 120 phr of white mineral oil #90 from Hanzhou Refinery, 50 phr of polypropylene homopolymer

(25MI) from Basel Corp, 80 phr of sodium sulfite from Shangdong Zhichuang Fine

Chemials, 6phr or USP grade sodium chloride from Fuwnag Pharmaceuticals were mixed thoroughly in a high speed mixer from Huaming Machinery. The mixture was then fed to a T20 twin screw extruder from Nanjing Ruiya Plastic Machinery at a temperature of 170 *C. The extruded strands were then cut into approximately 0.5 cm in diameter and 1 cm in length pieces. The pieces were then stored in a barrier bag purged with nitrogen gas and heat-sealed for future use. These pieces were labeled as Example 1 Original.

Example 2:

50 phr of SEBS polymer Taipol 3151 and 50phr of SBS polymer Taipol

(25MI) from Basel Corp, 80 phr of iron powder from Suzhou Jingsui Metallurgy

Co. Ltd., 6phr or USP grade sodium chloride from Fuwnag Pharmaceuticals were mixed thoroughly in a high speed mixer from Huaming Machinery. The mixture was then fed to a T20 twin screw extruder from Nanjing Ruiya Plastic Machinery at a temperature of 170 *C. The extruded strands were then cut into approximately 0.5 cm in diameter and 1 cm in length pieces. The pieces were then stored in a barrier bag purged with nitrogen gas and heat-sealed for future use. These pieces were labeled as Example 2 Original.

Example 3:

50 phr of SEBS polymer Taipol 3151 and SOphr of SBS polymer Taipol

(25MI) from Basel Corp, 4 phr of erucamide were mixed thoroughly in a high speed mixer from Huaming Machinery. The mixture was then fed to a T20 twin screw extruder from Nanjing Ruiya Plastic Machinery at a temperature of 180⁰C. During extrusion of the compound, a piece of te Example 1 Original or Example 2 Original was carefully inserted into the Example 3 molten extrudate stream so that the

Example 1 Original or Example 2 Original was fully encased by the Example 3 extrudate. The encased pieces consisted of Example 1 Original or Example 2

Original as the core and Example 3 as the skin layer. The pieces were then labeled as Example 1 Oxygen or Example 2 Oxygen with Example 1 Original or Example 2

Original as the core, respectively. The pieces were then stored in a barrier bag purged with nitrogen gas and heat-sealed. Some pieces of Example 3 were also taken as described in Example 1 and stored in the same manner. These were then labeled as Example 3 Original.

Example 4: lOOphr of a LDPE 1150A from Beijing Yangshan Petroleum Chemical, 80phr of Kraton G-1651 from Kraton Polymers, lOOphr of white mineral oil #90 from Hanzhou Refinery, 3 phr of a blowing agent HDlOl from Nanjing Huadu

Technology were mixed thoroughly in a high speed mixer from Huaming

Machinery. The mixture was then fed to a twin screw extruder from Nanjing Ruiya

Plastic Machinery at a temperature of about 170⁰C. The extruded strands were then cut into small pieces for future use. In a similar fashion, Example 2 mixture was made into small pieces, too. Example 2 and Example 4 pellets were melted and co-injected into cork shaped articles (see Figure 2) so that the outer skin was made of Example 4 material The synthetic corks made thereof were then labeled as Example 4 Oxygen. The synthetic corks were then stored in a barrier bag purged with nitrogen gas and heat-sealed. Some synthetic corks labeled as Example 4 Original (made entirely of Example 4 Original pellets) were also made and stored in the same manner.

The pieces of Example 1 Oxygen, Example 2 Oxygen, Example 4 Oxygen, Example 3 Original and Example 4 Original were subject to oxygen scavenging testing. The test was done by putting one piece into a 355 ml metal container with inside atmosphere maintained at 100% relative humidity. The container was filled with room air and sealed with a barrier stopper. The three specimens were approximately the same dimension and weight. The inside atmosphere was measured with oxygen level detector, RSS-5800 Oxygen Detector from Shanghai Leici Xingjing Instruments. After one (1) week of testing the inside atmosphere for Example 1 Oxygen level dropped from about 20.8% to about 14.8 whilst for Example 2 Oxygen dropped from 20.9% to 15.1%. The inside atmosphere for Example 3 Original remained the same, about 20.9%. The results indicate that Example 1 Oxygen and Example 2 Oxygen functioned to scavenge oxygen due to the core's composition; the skin layer did not scavenge oxygen. In a similar fashion, the oxygen level in the atmosphere in Example 4 Oxygen container was 14.2% in about 2 weeks while the control atmosphere in Example 4 Original was 20.9%. Hence we see a drop of oxygen level of about 5.7%.

These experiments prove a concept of my design of using an oxygen scavenging compound as the core and a polymeric compound as the skin layer of a closure. For those experienced in the art, it is obvious to use any oxygen scavenging compound as the core and any polymeric compound as the skin layer. It is also obvious to use the same oxygen scavenging compound as both the skin layer and core. For those experienced in the art, it is obvious to injection mold the core and the skin simultaneously or at a slight time delay to make the closure. It is also obvious to make the core through injection molding or extrusion process and then insert-mold the skin layer over the core to form the final closure or to put the skin made previously through some means over the core. It is also obvious, in case that the core and the skin layer compositions are the same, that a single forming processing would be enough to make the closure. It is still obvious to make the skin layer-core combination through any other methods. The closure thus made would be free from the worry of mold growth, free from crumbling, free from other undesirable properties and environmentally friendly of a natural cork. The closure of this invention is substantially different from the synthetic corks claimed in US 5,480,915 and US 5,904,965 due to the oxygen scavenging capability and particular design of this invention. [8]

The industrial applicability of this invention is wide. It can be used to make wine corks for the wine industry. The corks are to scavenge oxygen inside the wine bottle over time. The corks also would slow down or eliminate the oxygen ingress from out side the bottle. If appropriately made, corks of this invention would reduce or eliminate the use of sulfites inside the wine and potentially eliminate a health effect of wine due to sulfites. The invention can be extended to other packaging applications. [9]

Sequence List Text [10]

Claims

Claims[1] What is claimed is:

1. A molded closure for a container, particularly wine bottle, comprising (1), a skin layer made of a polymeric compound, the compound can either be foamed or not-foamed and

(2), a core made of a polymeric compound having oxygen scavenging capability. The compound can either be foamed or not-foamed.

2. It is preferred that the polymeric material of the skin layer of Claim 1 be made of a thermoplastic compound or plastic compound having elastic properties.

3. An oxygen scavenging polymeric compound having sodium sulfite/sodium chloride or iron powder/sodium chloride combination as oxygen scavengers. The compound is preferably a thermoplastic elastomer compound in nature or soft thermoplastics; it can be foamable or non-foamable.

4. The oxygen scavenging composition can preferably be composed of an SEBS compound or an SEEPS compound, alone or with any combination with an SBS compound.

5. Wherein, upon insertion of the said molded closure into a bottle or container, the said molded closure does not permit significant passage of oxygen from outside to the inside of the container. It can absorb an amount of oxygen from the inside of the bottle or container or from the liquid contained herein.

A polymeric closure for a container comprising a polymeric compound and another polymeric compound having oxygen scavenging capability and oxygen scavenging compositions are claimed. The formed closure is especially suitable for use as a wine cork in a wine bottle or container. The formed closure absorbs oxygen from the content of the container. The formed closure does not have the same contamination tendency as the natural cork does to the packaged wine. The formed closure can be removed from the bottle using a corkscrew without significant expansion, crumbling or disintegration.