EP0150894B1

EP0150894B1 - Flexible containers containing a liquid product and prevention of vacuum collapse therein

Info

Publication number: EP0150894B1
Application number: EP85300025A
Authority: EP
Inventors: Melzie Lee Robinson; James Carey Letton
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1984-01-06
Filing date: 1985-01-03
Publication date: 1988-05-18
Also published as: EP0150894A1; DE3562782D1; CA1237391A; ATE34405T1

Abstract

Vacuum collapse in packages containing oxygen-absorbing compositions is prevented by incorporating certain antioxidants into the compositions.

Description

The present invention relates to the packaging of oxygen-absorbing compositions in flexible containers, and more particularly, to improvements in the packaging of pine oil or other liquid oxygen-absorbing compositions in flexible plastic bottles.
According to the present invention, there is provided an article of manufacture characterized by

A. a sealed flexible container containing,
B. a liquid cleanser product containing an oxygen absorbing reaction component in an amount sufficient to cause vacuum collapse of said container due to the absorption reaction of oxygen from container headspace, said oxygen absorbing component being selected from terpenes and terpenoids, and
C. a compatible antioxidant in an amount sufficient to stabilize said oxygen absorbing component and thereby prevent said oxygen absorption and vacuum collapse, said antioxidant being soluble in the liquid and being selected from substituted-phenolic compounds.

An object of the invention is to provide for filling bottles or analogous containers with liquid cleansers as defined which can be introduced into the containers without complete expulsion of air.
A further object of the invention is to provide for filling bottles or like containers with liquid cleansers as defined and which are to be stored in containers consisting of a material which is unable to withstand atmospheric pressure in response to a reduction of pressure in its interior to a relatively low subatmospheric pressure.
A flexible container is defined herein as one which will deform (indent) when the inside pressure is reduced to the extent that the pressure differential between the outside and the inside is equal to or less than 26.7 kPa (200 mmHg) under standard conditions. Of course, under nonstandard conditions the differential will vary. Many bottles which are more flexible will indent when the differential is less than 20.0 kPa (150 mm Hg), and still others will indent or collapse when the differential is 13.3 kPa (100 mm Hg) or less. Polyvinyl chloride (PVC) bottles are a preferred type of bottle for packaging pine oil-containing cleansers. Depending upon bottle wall thickness and/or design, a PVC bottle will collapse when the differential is less than 26.7 kPa (200 mm Hg). 1n other words, if oxygen is in the headspace of the container, it is likely to react with the oxygen-absorbing liquid and thereby collapse the bottle upon storage before or after use.
It has been observed that after flexible containers are filled with pine oil-containing liquid, the flexible container is likely to collapse in response to absorption of oxygen from its interior headspace.
The present invention is applicable to liquid cleanser products wherein the oxidizable component is selected from terpenes and terpenoids, and wherein the antioxidant is a soluble substituted-phenolic compound. The antioxidants are effective when the oxidizable component is present in the liquid at a level of 40 to 400 times the weight of the antioxidant.

Absorbing Liquids Containing Oxygen Reacting Components

In accordance with the present invention, it has been found that liquid cleansers which contain substantial amounts of a terpene can cause vacuum collapse in flexible containers. For the purpose of this invention, terpenoids, i.e., the oxygenated derivatives of the terpene hydrocarbons, including the alcohols, ketones, aldehydes, acids and esters derived from the terpenes can also be used and are to be included within the general term "terpene". Useful terpenes include the acyclic, monocyclic and bicyclic terpenes. Although the C₁₄-terpenes have been found to be most effective, sesqui-terpenes and diterpenes are also useful. Examples of such compounds include alpha-terpenes, beta-terpenes, pheliandrene, myricene, ocimene, tricyclene, terpinolene, terpinoyl acetate, isoborneal, dipentene, menthol, menthone, carene, limonene, sylvestrene, sabinene, camphene, alpha-farnesene, zingiberene, carylophyllene, geraniol, nerol, linalool, neral, citronellal, alpha-terpineol, 1,8-cineole, ascaridole, camphor, thujone, verbenone, fenchone, isobornyl acetate, farnesol, abietic acid and its salts and esters. A variety of naturally-occurring terpene mixtures, derived from various plant sources, have also been found useful, for example from pine tree oil, citrus fruits, the lemon terpenes, orange terpenes, lemon grass oil and lime oil distillate. Although the higher terpenes, e.g., the diterpenes and sesqui-terpenes, can be utilized, the terpene hydrocarbons and terpenoids, including the basic terpene -C_'o group are preferred.

The Antioxidant

The substituted-phenolic antioxidant compounds useful in accordance with the present invention include any of that class of compounds which retard oxidation. They may also retard deterioration and/or rancidity.
Antioxidants include the polyphenols, such as the hydroquinones, especially the ortho- and para- polyphenols, such as pyrocatechol and pyrogallol; poly-substituted "masked" and "hindered" phenols, especially those which are substituted in the 2, 4 and 6-positions, such as 2-, 4-, 6-trialkylphenols; neutral esters of hydroxybenzoic acids, such as alkylhydroxybenzoic acids, p-hydroxybenzoic acid, gallic acid, and salicylic acid; bisphenols, aminophenols; and condensed hydroxyaromatics, such as naphthols. The preferred antioxidant is 2,6-di-tert-bytyl-4-methylphenol (BHT).
While not being bound to any theory, it is believed that the free radical stabilization of a terpene by BHT can be illustrated as follows:

1 . Hydrogen Transfer (antioxidant is oxidized)
2. Resonance Stabilization (in equilibrium)
The stabilized terpene, RH, does not react with oxygen. The free radical of the antioxidant resonates, rather than reacts with oxygen. The system is stabilized regardless of theory.

One part of an antioxidant, such as BHT, can be used to prevent vacuum collapse in flexible containers containing liquids which have from 40 to 400 times the weight of oxygen reacting/absorbing components, such as pine oil.
A preferred liquid composition of the invention is a stable homogeneous liquid detergent comprising:

a) from 4% to 30%, preferably from 5% to 15% of said terpene or terpenoid oxygen absorbing component;
b) from 0.05% to 1 % of BHT;
c) from 1% to 10% by weight of an anionic synthetic surfactant;
d) from 1% to 20% by weight builder selected from alkali metal pyrophosphates, citrates and ethylenediamine tetraacetates;
e) from 1% to 5% by weight isopropyl alcohol;
f) from 1 % to 11 % by weight of a hydrotrope selected from water-soluble salts of cumene, xylene and toluene sulfonic acids; and
g) water.

In a preferred aspect of the present invention, it has been found that stable, built, aqueous, synthetic detergent compositions containing pine oil can be formulated by utilizing suitable amounts of pine oil compatible antioxidant free radical scavenger in the composition to stabilize the pine oil against reaction of oxygen in the headspace of flexible containers.
Anionic surfactants are a well-known class of surface active chemicals and any of those known in the art can be used in the present compositions.
The most common anionic surfactants can be broadly described as the water-soluble salts, particularly the alkali metal salts, of organic sulfuric acid reaction products having in their molecular structure an alkyl or alkaryl radical containing from about 8 to 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. (Included in the term "alkyl" is the alkyl portion of higher acyl radicals.) Important examples of the anionic surfactants which can be employed in the practice of the present invention are the sodium or potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (C₈―C₁₈ carbon atoms); sodium or potassium alkyl benzene sulfonates; in which the alkyl group contains from about 9 to about 15 carbon atoms, (the alkyl radical can be a straight or branched aliphatic chain); paraffin sulfonate surfactants having the general formula RS0₃M, wherein R is a primary or secondary alkyl group containing from about 8 to about 22 carbon atoms (preferably 10 to 18 carbon atoms) and M is an alkali metal, e.g., sodium or potassium; sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of sulfuric acid esters of the reaction product of one mole of a higher fatty alcohol (e.g., tallow or coconut oil alcohols) and about 1 to about 10 moles of ethylene oxide; sodium or potassium salts of alkyl phenol ethylene oxide ether sulfates with about 1 to about 10 units of ethylene oxide per molecule and in which the alkyl radicals contain from about 8 to about 12 carbon atoms; the reaction products of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil; sodium or potassium salts of fatty acid amides of a methyl tauride in which the fatty acids, for example, are derived from coconut oil, and sodium or potassium alpha-acetoxy or alpha-acetamido-alkanesulfonates where the alkane has from 8 to 22 carbon atoms.
Mixtures of anionic surfactants can also be used.
Additional anionic synthetic surfactants are disclosed in McCutcheon's Detergents and Emulsifiers, North American Ed. (1980).
Particularly preferred anionic surfactants are the alkali metal C₁₀―C₁₈ alkyl sulfates and the alkali metal C₉―C₁₅ linear alkyl benzene sulfonates, especially the C_ll-C_l3 linear alkyl benzene sulfonates.
Anionic surfactants are generally present at levels of from 1% to 10%, preferably from 4% to 7% in the compositions herein.
The anionic surfactant functions as a detergent material and also acts in conjunction with the isopropyl alcohol to keep the pine oil solubilized in the aqueous system.
In addition to the anionic surfactants, which are an essential component of the compositions herein, said compositions can also contain nonionic surfactants (e.g., the adducts of fatty alcohols or alkyl phenols with from 1-30 moles of ethylene oxide), · amphoteric surfactants, (e.g., sodium-3-dodecylamino- propionate) and/or zwitterionic surfactants. See US-A-3,664,961.
Sequestering builders are used in the preferred compositions herein at levels of from 1% to 20%, preferably from 1% to 8%, most preferably 5% to 8%. The sequestering builders herein are selected from alkali metal pyrophosphates (e.g., K₄P_z0,) alkali metal citrates (e.g. sodium citrate) and alkali metal ethylenedianine tetraacetates (e.g., Na₄EDTA, Na₂H₂EDTA). Alkali metal pyrophosphate is the preferred builder. This material provides alkalinity as well as sequestering water hardness ions when the composition is diluted with tap water to prepare dilute usage solutions. If EDTA or citrate is used as the sequestering builder and it is desired that the composition be alkaline, alkaline salts such as alkali metal carbonates, orthophosphates and silicates can be added.
Pine oil is used in the preferred compositions herein at levels of from 4% to 30%, preferably from 5% to 15%. Pine oil is most commonly obtained by extraction or steam distillation of the wood of pine trees. It has excellent solvent properties for greasy soils and also functions as an odorant and antimicrobial agent in the compositions herein. Pine oil is a mixture which primarily comprises terpene alcohols. The term "pine oil" as used herein encompasses the terpene alcohols per se, as well as the mixture of said alcohols which naturally occurs in pine oil.
Isopropyl alcohol is present in the preferred compositions herein at levels of from 1% to 5%, preferably from 3% to 5%. The isopropyl alcohol functions along with the anionic surfactant to keep the pine oil solubilized in the aqueous system.
US-A-3,360,476 discloses glycols as solubilizers for pine oil in built, soap-based aqueous liquid detergents. The compositions herein can be substantially free of glycols.
The water:-soluble cumene, xylene or toluene sulfonate salt is present in the preferred compositions herein at levels of from 5% to 11 %, preferably from 7% to 11 %. The salts which are preferred are the alkali metal salts, especially sodium and potassium. These sulfonate salts serve as hydrotropes to keep the sequestering builders in solution in the composition.
When formulating preferred compositions herein with amounts of builder and pine oil which are at the high ends of the ranges specified herein, it is generally necessary to use amounts of anionic surfactant, hydrotrope and isopropanol which are toward the high end of the ranges stated herein for these respective ingredients, in order to secure stable compositions.
Various optional ingredients may be included in the present compositions. These include, for example, dyes, perfumes, and the like. Antimicrobial ingredients to supplement the antimicrobial performance of pine oil are particularly preferred optional ingredients. These include materials such as ortho phenyl phenol, 2-benzyl-4-chlorophenol, 4-chloro-2-cyclopentylphenol and di-C_a-C_1o alkyldimethyl ammonium chloride. These supplemental antimicrobial agents are generally used at levels of from 0.1% to 4% in the compositions herein.
When 2-benzyl-4-chlorophenol is used in the compositions herein, a special solubilizer for this material is preferably also present. The solubilizer is sodium-n-decyl diphenyloxide disulfonate (Dowfax^O 3B-2, Dow Chemical Company), and is generally used at a level which is about one-fourth the level of 2-benzyl-4-chlorophenol. For purposes of describing the present invention, the term "anionic surfactant" shall not be understood as including sodium-n-decyl diphenyloxide disulfonate. When this special solubilizer for 2-benzyl-4-chlorophenol is used in the compositions herein, its presence is in addition to the anionic surfactant.
The balance of the compositions herein is water. Preferably the compositions are prepared with water of low mineral content such as softened or distilled water.
Although the compositions herein are inherently clear, they can be opacified with known opacifying agents such as latex compounds (e.g., Lytrons^@ from Monsanto Company); microcrystalline cellulose (e.g., AvicelO from FMC Corporation) and synthetic silicates (e.g. Microcel® from Johns-Manville Co.)
The invention will be further illustrated by the following examples.

EXAMPLE I (Comparative)

A composition has the following formula:
To make this composition, the following raw materials are added, in the order listed, to a 1000 ml beaker agitated by a small mechanical stirrer:
Each ingredient is allowed to agitate thoroughly prior to addition of the next ingredient. This order of addition yields a physically stable, clear homogeneous composition; however, other orders of addition will suffice. Portions of the liquid composition are stored in flexible, capped 0.425 kg (15 oz) (0.4 liter) PVC bottles. The bottles are filled to levels of about one-third to two-thirds. After two months of storage under ambient conditions the bottles collapse (indent). The pressure differential is about 13.3 kPa (100 mm Hg).

Example II

Same as Example I, except that BHT is added at a level of about 0.8% by weight of the pine oil, which is about 0.08% by weight of total composition. After two months storage there is no deformation or indentation of the PVC bottles.

Example III

Same as Example I, except that BHT is added at a level of about 1.6% weight of the pine oil, which is about 0.016% by weight of total composition. After two months storage there is no deformation or indentation of the PVC bottles.

Claims

1. An article of manufacture characterized by

A. a sealed flexible container containing,

B. a liquid cleanser product containing an oxygen absorbing reaction component in an amount sufficient to cause vacuum collapse of said container due to the absorption reaction of oxygen from container headspace, said oxygen absorbing component being selected from terpenes and terpenoids, and

C. a compatible antioxidant in an amount sufficient to stabilize said oxygen absorbing component and thereby prevent said oxygen absorption and vacuum collapse, said antioxidant being soluble in the liquid and being selected from substituted-phenolic compounds.

2. An article according to Claim 1 wherein said contained liquid is a stable homogeneous aqueous liquid detergent composition comprising:

a) from 4% to 30%, preferably from 5% to 15% by weight of said oxygen absorbing component;

b) from 0.05% to 1% by weight of said antioxidant which is 2,6-di-tert-butyl-4-methylphenol (BHT);

c) from 1% to 10% by weight of an anionic synthetic surfactant;

d) from 1% to 20% by weight builder selected from alkali metal pyrophosphates, citrates and ethylenediamine tetraacetates;

e) from 1% to 5% by weight isopropyl alcohol;

f) from 5% to 11 % by weight of a hydrotrope selected from water-soluble salts of cumene, xylene and toluene sulfonic acids; and

g) water.

3. An article according to Claim 2,-wherein the oxygen absorbing component is pine oil.

4. An article according to Claim 3 wherein the level of anionic surfactant is from 4% to 7% by weight, the level of builder is from 5% to 8% by weight, the level of pine oil is from 10% to 15% by weight, and the level of antioxidant is from 0.05% to 0.5% by weight.

5. An article according to Claim 4 wherein the level of said pine oil is from 40 to 400 times the weight of the antioxidant.