WO1995016366A1

WO1995016366A1 - Liner composition for a closure element for a fluid container

Info

Publication number: WO1995016366A1
Application number: PCT/US1994/014189
Authority: WO
Inventors: Mahmood R. Rassouli; Anthony Irwin
Original assignee: Zapata Technologies, Inc.
Priority date: 1993-12-14
Filing date: 1994-12-08
Publication date: 1995-06-22
Also published as: AU1305195A

Abstract

A liner composition for a potable fluid container closure element which includes an unactivated hydrazide, preferably a carboxylic acid hydrazide or a sulfonyl hydrazide such as 4,4' -oxybis(benzenesulfonyl hydrazide) for preventing off-flavors due to the presence of aldehydes in the fluid. Also, a potable fluid container of a reservoir element for containing a potable fluid, the reservoir element having an opening, a closure element capable of being attached to the opening, and the liner composition associated with the closure element. Also, a method of improving the taste of a potable fluid such as bottled water by use of the container and one of the previously described liner compositions associated therewith.

Description

LINER COMPOSITION FOR A CLOSURE ELEMENT FOR A FLUID CONTAINER

TECHNICAL FIELD

The present invention relates to a plastic liner composition for use in closures for potable fluid containers such as bottled water. The liner includes an additive which protects against the development of off-flavor in the potable fluid that would otherwise result from the reaction of ozone 0 in the fluid with the plastic liner composition or components thereof.

BACKGROUND OF THE ART

In order to produce bottled drinking water, it is 5 necessary to disinfect the water so as to remove the microorganisms that would otherwise grow therein. In the past, water was disinfected using chlorine. However, the use of chlorine invariably resulted in the production of trihalomethanes such as chloroform which have been shown to pose a serious health risk. Alternatively, water bottling companies can use ozone as a disinfectant instead of chlorine to kill any microorganisms present in the water itself. Thus, the bottled water usually contains ozone in trace amounts. Typically, ozone is present in an amount of about _ 0.1 to 0.4 mg/1. These trace amounts kill the microorganisms so that it is not necessary for the water to be pasteurized. In addition, ozone oxidizes many nuisance compounds or contaminants in water supplies.

Drinking water standards in the United States specify ₀ that drinking water should not have any smell or taste. As shown by C. Anselme et al. in J. American Waterworks Association. 80. 45-51 (1988), the intensity of a fruity off- flavor correlates strongly with the total concentration of aldehydes present in the water. _ Ozone reacts with compounds which contain double bonds, such as alkenes, yielding corresponding aldehydes as the major oxidation product. A source of double bond containing precursors that react with ozone in bottled water is the polymeric cap liner of the container. Polymeric cap liners typically contain a number of plasticizers, heat stabilizers, lubricants, antioxidants, blowing agents and pigments, some or all of which contain double bonds which are susceptible to attack by ozone. For example, the liner formulations for twist-off caps typically comprise amide-type lubricants. The double bonds in such amides are readily susceptible to attack by ozone, resulting in off-flavor producing, medium-chain length aldehydes. Also, fatty acids or derivatives of fatty acids of liner compositions react with ozone to form off- flavored aldehydes. Other compounds often found in polymeric cap liners which are susceptible to attack by ozone include activated aromatic compounds such as phenols, and other double bond-containing compounds such as ketones, amides, erucic acid, etc. The resulting aldehydes are responsible for the fruity tastes and odors often found in bottled water.

While one solution to this problem is to remove the compounds that are reactive with ozone, this solution is not practical since the liner would not possess the desired properties to properly seal the bottle. Also, it is not possible to remove all remaining traces of ozone from the water, because it is added in an amount which is in excess of that needed to oxidize microorganisms and other contaminants which may be present in the water.

Accordingly, a need exists for an improved liner which can protect against the development of an off-flavor in bottled water or other fluids.

SUMMARY OF THE INVENTION

This invention is directed to a liner composition for a closure element of a container for potable fluids such as water. The liner composition includes an unactivated hydrazide in amount sufficient to protect against the development of off-flavor in a potable fluid in the container. The preferred hydrazide is a sulfonyl hydrazide, such as 4-4'-oxybis (benzenesulfonyl hydrazide) ("OBSH") or p-toluene sulfonyl hydrazide. Also, carboxylic acid hydrazides can be used.

The invention is also directed to a potable fluid container comprising a reservoir element for containing fluid, which element has an opening, a closure element capable of being attached to the opening, and the above- described liner composition associated with the closure element. Generally, the closure has a recessed portion for receiving the container opening, and the liner is placed within the recess of the closure element between the container opening and the closure element for sealing the fluid within the container.

Another aspect of the invention relates to a method of improving the taste of a bottled fluid such as water by containing the fluid in the above potable fluid container and associating the above liner composition with the container so that the hydrazide can react with residual ozone in the fluid.

DETAILED DESCRIPTION OF THE INVENTION

Conventional bottle closure linings are made of a thermoplastic material, such as polyvinyl chloride ("PVC") , ethylene vinyl acetate ("EVA") , polyolefins such as polyethylene ("PE") or blends thereof. In order to attain the optimum combination of moldability, resilience, sealability, etc., these materials are formulated to include plasticizers, heat stabilizers, lubricants, blowing agents, antioxidants, pigments and other additives. These additive components are well known to one skilled in the art so that a detailed description is not needed herein.

It is known to use hydrazides such as OBSH as a blowing agent in the liner composition of a closure element of a potable fluid container. Blowing agents are chemicals that are added to plastics or rubbers for generating inert gas upon decomposition, causing the resin to assume a cellular structure. For example, adding OBSH to the liner of a closure element of a container for bottled water and decomposing the OBSH to produce small bubbles (foam) of nitrogen gas which are trapped inside the liner provides a sponginess to the material. When used as a liner of a closure element of the container, an improved seal is achieved.

In the present invention, the liner composition comprises an unactivated hydrazide in an amount sufficient to protect against the development of off-flavor in a potable fluid in the container. For the purposes of the present invention, "unactivated hydrazide" is hydrazide which has not been subjected to a decomposition reaction. This can occur by either adding an amount of hydrazide beyond that which is needed for use as a blowing agent or by processing the liner so as to not decompose the hydrazide compound which is present.

Hydrazides of organic sulfonic acids have been found to be useful in the present invention. Both aliphatic and aromatic sulfonic acids can be used, with one or both -NH₂ groups of the hydrazine molecule being substituted with alkyl or aryl radicals. The most preferred compound is a sulfonyl hydrazide, such as OBSH, since it has FDA approval for applications and articles which come into contact with food or beverages. Other sulfonyl hydrazides such as p-toluene sulfonyl hydrazide can be used, if desired. Thus, the useful hydrazides can contain one or more -NH₂ groups, where the hydrogens may optionally be substituted by other organic moieties.

Other hydrazides which may be used to reduce the off- flavor of bottled water include carboxylic acid hydrazides of the general structure shown below.

where R is hydrogen, a straight chain or branched alkyl or alkenyl group of 1 to 20 carbon atoms, a phenyl group, which is substituted or unsubstituted, or the like.

The only restrictions on the hydrazides for use in the liners of the present invention are that the hydrazide be compatible with the material and other components of the liner and that the compound be FDA approved for use in contact with the fluid to be ingested. Preferably, the hydrazide is present in the liner composition in an amount of from about 0.1 to about 1.0% by weight of the composition.

Since the liner composition may also include a hydrazide for use as a blowing agent, the composition must be formulated so that the amount of hydrazide decomposed is less than the total amount of hydrazide that is added to the liner composition. This decomposition may be activated by an activator or by heat. In the present invention, an activator for decomposing the hydrazide is added in an amount that is less than that necessary to activate the total amount of hydrazide in the liner composition. Examples of typical activators include carbonates, glycols, ureas, acids, alkanolamines, oxidizing agents such as peroxides. In particular, carbonates such as sodium carbonate are preferred activators. The present invention may also include at least one blowing agent other than the unactivated hydrazide, if desired.

The liner composition is generally made of a material which is permeable to gases and water or water vapor. As noted above, this material would typically be a polymer, such as a thermoplastic resin. Thermoplastic resins of polyolefins such as PE and the like, PVC, EVA, and the like would allow gases such as oxygen or ozone, and water or water vapor to pass into and through the liner. The unreacted hydrazide of the present invention protects against the development of off-flavors which would otherwise result from the formation of aldehydes due to the reaction of ozone present in the potable fluid with prior art liner compositions or components thereof. For liner manufacture, the disclosure of U.S. Patent No. 5,202,052 is expressly incorporated herein by reference hereto. The preferred hydrazide compound may be admixed into the liner or can be coated thereon or otherwise associated therewith.

Preferably, the potable fluid container of the present invention contains a potable fluid, such as water, which has ozone added thereto. Ih the case of water, the ozone is preferably added in trace amounts, such as from about 0.1 to 0.5 mg/1.

EXAMPLES

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed nonlimiting examples of the present invention.

Example 1

Seven 200 ml water samples were each ozonized as follows. Seven samples of 206 + 0.5 grams of distilled water were each poured into a clean 7 ounce bottle. A Sander Ozonizer Model 25, having 25 mg per hour capacity was connected to a 100% oxygen tank via a silicone rubber tubing. The outlet of the ozonizer was connected to Teflon tubing via silicon rubber tubing to minimize the exposure of the silicon rubber to the ozone. The Teflon tubing was connected to a glass gas dispersion tube. Catalog Number 9435A of Ace Glass, Inc., Vineland, NJ, via silicone rubber tubing. The glass gas dispersion tube was immersed in water. The ozone concentration was controlled with oxygen flow and flow time. An oxygen flow of 115-121 ml with 25 mg per hour setting of ozonizer resulted in 0.4 to 0.5 mg/1 (ppm) of ozone in the 7 ounce bottle of water after 3.5 minutes. The concentration of ozone was determined with an Ozone Test Kit, Hach Chemical Co. Model OZ-2, Catalog No. 20644-00, Loveland, Co. The analytical range of ozone detection is 0.1-2.3 mg/1. To determine whether the components of the liner are the source of off-flavor in the water samples, the components are separately added to the samples, each in an amount of 2mg. The composition of the liner is given below in Table 1. TABLE 1

Component Parts fibs)

PVC Resin 200

Primary Plasticizer 153 Secondary Plasticizer A 11.8

Stabilizer 2

Lubricant Package 3.37

Specifically, 2 mg of each one of OBSH, the primary plasticizer, the secondary plasticizer and the three components of the lubricant package are separately added to six samples, respectively. Lubricant #1 and lubricant #2 are amides of an unsaturated fatty acid, and lubricant #3 is a paraffin wax. A seventh sample was used as a control, having nothing added thereto. The bottles were immediately crowned and later tested for flavor.

The final ozone concentration before crowning was determined to be 0.4 to 0.5 mg/1. The bottles were stored at room temperature for two days. Colorimetric analysis showed that the control sometimes contained unreacted ozone after two days, while no ozone remained in any of the bottles to which the additional components had been added.

The samples were then evaluated by a taste panel, evaluating the off-flavor intensity of the samples. The results were such that the sample containing OBSH and the control had approximately the same flavor, which flavor was less than for the samples containing the secondary plasticizer and the lubricants, with the sample containing lubricant #2 having the strongest flavor of all the samples evaluated. Example 2

Three samples of distilled water were bubbled with ozone as in Example 1 to contain a concentration of 0.4-0.5 mg/1 ozone and then were crowned in a bottle with the following liners having the following formulations:

TABLE 2

LINER FORMULATION

Component A B C

PVC Resin 200 200 200

Prim. Plast. 144 153 153

Sec. Plast. A 13.2 11.8 -

Stabilizer - 2 0.74

Anti-Oxidant 1.6 - -

OBSH 1.4 - -

Sec. Plast. B - - 11.8

Lubricant 9.0 3.37 5.0

Package

Pigment - - 0.16

Drying agent 0.67 - -

The bottles were stored at 22°C for four days and then tasted by a taste panel for evaluating the off-flavor intensity of the samples. The results were that liner A had no off-flavor, liner B had a very weak off-flavor and liner C had a strong off-flavor. The superiority of liner A, despite its lubricant package, is attributed to the presence of OBSH.

Example 3

In order to evaluate the effect of increasing temperature and time of storage, 3 bottles of distilled water were ozonized as in Example 1 and were crowned with liners B, B + (0.2% OBSH) and C.

The bottles were stored for 56 days at 30°C and were evaluated for off-flavor by a taste panel. The results were as follows: TABLE 3

LINER Off-Flavor Intensity ( 0-3 Scale )

C 3 B 2 B + ( 0.2% OBSH) 1

The OBSH containing sample was found to be clearly superior to the other samples.

Example 4

Three bottles of distilled water were ozonized as in Example 1 to contain 0.4 mg/1 ozone. The bottles were capped with the following closure tapes which were made from a copolymer of ethylene vinyl acetate comprising of 10% vinyl acetate having the following formulations:

TABLE 4

CLOSURE TAPE FORMULATIONS

Component CT-1 CT-2 CT-3

Virgin EVA 60% 100% 100%

Regrind EVA 40%

OBSH - 0.2

After storage for four days at room temperature, taste tests found that CT-1 had weak off -flavor intensity, CT-2 had moderate off -flavor intensity, and CT-3 had no off -flavor intensity.

Example 5

Six bottles of water were ozonized as in Example 1 to contain a concentration of 0.4-0.5 mg/1 ozone. The bottles were sealed with crown liner elements A, B, B+(0.2% OBSH) and with closure tapes CT-1, CT-2, and CT-3. The bottles were then heated at 30°C for 30 days. A taste panel then evaluated the taste of each sample for off-flavor intensity on a scale of 0-3, with 0 having no off-flavor and 3 having an intense off-flavor. The results are as follows.

TABLE 5

CLOSURE ELEMENT OFF-FLAVOR INTENSITY

A 2 . 0

B 2 .4

B + ( 0.2% OBSH ) 1. 7

CT-1 2 .0

CT-2 1. 6

CT-3 0. 6

The intensity of off-flavors of the closure tapes increased for each sample when compared to the four day, room temperature test examples. However, some protective effect of OBSH was still evident.

Example 6

Three bottles of water were ozonized as in Example 1 to maintain a concentration of 0.4 mg/1 of ozone. The bottles were sealed with the following crown liner elements.

TABLE 6

FORMULATION

Coπroonent D I Σ

PVC RESIN 200 200 200

PRIMARY PLASTICIZER 153 153 153

SECONDARY PLASTICIZER A 11.8 11.8 11.8

STABILIZER 2 2 2

OBSH - - 0.7

LUBRICANT PACKAGE 3.37 1.28 3.37

These three bottles were evaluated for off-flavor intensity after storage for 4 days at room temperature. The taste of the formulation having the OBSH was found to be the cleanest, while the other formulations were found to have oxidized, aldehyde flavors.

Example 7

4 bottles of distilled water were ozonized as in Example 1 and were crowned with the following liners having the following compositions.

TABLE 7

LINER FORMULATION

Component G H

PVC Resin 200 200

Primary Plasticizer 164.8 164.8

Secondary Plasticizer A - -

Stabilizer 2 2

OBSH - 1.85

Lubricant Package 3.37 3.37

The bottles were stored for 5 days at room temperature and were evaluated for off-flavor by a taste panel. The results, based on a scale of 0-3, were as follows.

TABLE 8

LINER OFF-FLAVOR INTENSITY

G 1.5

H 0.3

Formulation H, containing 0.5% OBSH based on the total weight of the liner formulation, was unanimously rated the best by the panel.

Although the present invention has been described in detail, it is clearly understood that the same is by way of example only and is not to be taken by way of limitation, the scope of the present invention being limited only by the terms of the appended claims.

Claims

THE CLAIMSWhat is claimed is:

1. A liner composition for a potable fluid container closure element, the liner composition comprising a polymer containing an unactivated hydrazide in an amount sufficient to protect against the development of off-flavor in a potable fluid in the container.

2. The liner composition of claim 1, wherein the hydrazide is a sulfonyl hydrazide.

3. The liner composition of claim 1, wherein the hydrazide is a carboxylic acid hydrazide.

4. The liner composition of claim 1, wherein the hydrazide is 4,4'-oxybis(benzenesulfonyl hydrazide) .

5. The liner composition of claim 1, wherein the hydrazide is present in an amount of from about 0.05 to about 2% by weight of the liner composition.

6. The liner composition of claim 1 further comprising an amount of hydrazide not decomposed for use as a blowing agent.

7. The liner composition of claim 1, wherein the polymer is a thermoplastic resin compound selected from the group consisting of a pol.yolefin, polyvinyl chloride, ethylene-vinyl acetate or a mixture thereof.

8. The liner composition of claim 1 further comprising one or more of a plasticizer, a heat stabilizer, a lubricant, an antioxidant or a pigment.

9. The liner composition of claim 1, which further comprises at least one blowing agent other than the unactivated hydrazide.

10. The liner composition of claim 1, which further comprises a blowing agent and the hydrazide which is not decomposed present as a portion of the blowing agent.

11. A potable fluid container comprising a reservoir element for containing a potable fluid, said reservoir element having an opening, a closure element having a recess and being capable of being attached to the opening, and the liner composition of claim 1 associated with the closure element.

12. The potable fluid container of claim 11, wherein the potable fluid has ozone added thereto.

13. The potable fluid container of claim 11, wherein the potable fluid is water.

14. The fluid container of claim 13, wherein ozone is added in an amount of from about 0.1 to 0.5 mg/1 and the unreacted hydrazide is present in the liner composition in an amount of about 0.1 and 1% by weight of the liner composition.

15. A method of improving the taste of a potable fluid in a container which comprises containing the potable fluid within a container and associating the liner composition of claim 1 with the container.

16. The method of claim 15 which further comprises providing the container with a closure element having a recess and placing the liner in the closure element recess.

17. The method of claim 15 wherein the potable fluid is water and which further comprises treating the water with ozone to provide a residual amount of about 0.1 to 0.5 mg/1.

18. The method of claim 17 which further comprises providing the hydrazide in the liner composition in an amount of about 0.1 to 1% by weight.

19. The method of claim 18 which further comprises selecting the unactivated hydrazide to be a sulfonyl hydrazide.

20. The method of claim 19 which further comprises selecting the hydrazide to be 4,4'- oxybis(benzene sulfonyl hydrazide).

21. The method of claim 18 which further comprises selecting the unactivated hydrazide to be a carboxylic acid hydrazide.