(19)
(11) EP 0 666 307 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
09.08.1995 Bulletin 1995/32

(21) Application number: 94201633.8

(22) Date of filing: 08.06.1994
(51) International Patent Classification (IPC)6C11D 3/39
(84) Designated Contracting States:
AT BE CH DE DK ES FR GB GR IE IT LI LU NL PT SE

(30) Priority: 03.02.1994 EP 94870018

(71) Applicant: THE PROCTER & GAMBLE COMPANY
Cincinnati, Ohio 45202 (US)

(72) Inventors:
  • Rapisarda, Dario
    I-95030 Mascalucia CT (IT)
  • Trani, Marina
    I-00136 Rome (IT)

(74) Representative: Engisch, Gautier et al
Procter & Gamble European Technical Center N.V. Temselaan 100
1853 Strombeek-Bever
1853 Strombeek-Bever (BE)


(56) References cited: : 
   
       


    (54) Packaged liquid bleach compositions


    (57) The invention is based on the finding that bulging of a container containing a liquid aqueous bleach composition and comprising hydrogen peroxide can be prevented by further incorporating dipicolinic acid in said composition.


    Description

    Technical field



    [0001] The present invention relates to packaged aqueous liquid bleach compositions which comprise peroxygen bleaches.

    Background



    [0002] Aqueous liquid bleach compositions comprising peroxygen bleaches are well known in the art. It is well known that such compositions are not fully compatible with all packaging materials. Specifically, such compositions may cause so-called bulging problems when they are packaged in containers made out of deformable materials, typically thermoplastic materials. Indeed, the peroxygen bleach in the composition decomposes with time so as to generate oxygen in the composition. The released oxygen builds up pressure inside the container which eventually deforms, i.e. bulges. The problem is more acute in warm countries where decomposition is favored by heat.

    [0003] Known solutions to this problem are specific container designs as in EP 534 009 and EP 572 722. Indeed bulging can be substantially reduced or even eliminated by selecting specific curvatures for the containers, generally the base of the containers. This, however, has the drawback of limiting flexibility in designing containers. Also, this solution may not be sufficient in extreme conditions such as when the contained composition comprises a high concentration of peroxygen bleach and/or when the container with its contained composition are exposed to extremely warm atmospheric conditions.

    [0004] Another solution is the use of so-called venting caps which let gasses out from the containers, but not liquids. Such caps prevent the building of pressure inside the containers. A variety of such caps have been described in the art, but they all have the drawback that they are expensive to make, either because they require sophisticated construction from several parts, or because they require the use of specific materials.

    [0005] A third type of solution is the use of so-called leaking caps, where the gasses are let out of the bottles for instance through the threads of the cap, between the inner wall of the cap and the outer wall of the container onto which the cap is screwed. This has the drawback of letting not only gasses through but also some of the liquid contained in the container.

    [0006] There is thus a strong need for providing another solution to the bulging problem.

    [0007] In response, we have found that bulging can be avoided by including a minor amount of dipicolinic acid (hereafter DPA) in the liquid aqueous bleach contained in the container. This is unexpected because extended testing has shown that other compounds which are known to stabilize peroxygen beaches, for instance butyl hydroxy toluene do not provide the anti-bulging benefit even at higher levels, whereas DPA does. We speculate that this may be due to a unique interaction mechanism between DPA and the O2 molecules, where DPA traps the O2 molecules.

    Summary of the invention.



    [0008] In one aspect, the invention encompasses a closed deformable container containing a liquid aqueous composition comprising a peroxygen bleach and an effective amount of dipicolinic acid.

    [0009] In another aspect, the invention encompasses the use of dipicolinic acid, in a liquid aqueous bleach composition having a pH of from 1 to 5 and comprising a peroxygen bleach, to prevent the bulging of the deformable container containing said composition.

    Detailed description of the invention



    [0010] A first essential element of the present invention is the closed deformable container which contains the liquid bleach composition. Preferably, the containers for use herein are bottles, i.e. they comprise a body portion and a neck. Indeed, the bulging problem is particularly a nuisance when using bottles, as the bottle deforms at its base when pressure builds up, and this compromises the stability of the bottle upon standing. It is not unusual to observe that the base is deformed to the point where the container cannot stand on its base at all. One will appreciate that this is a problem not only for the consumers but also for the trade. Bulging also happens in other containers such as bulk containers and is also a problem there, but to a lesser extent. Accordingly, preferred containers herein are bottles comprising a body portion comprising a base on which the bottle stands, and a neck portion which comprises means for attaching a closure. Said bottles may of course comprise a variety of other items, typically handles.

    [0011] The containers herein are closed containers. By closed, it is meant herein that pressure can be generated inside the container, i.e. the container does not have a free communication with the ambient. This definition includes closures which allow a partial communication with the ambient, i.e. so-called venting caps inasmuch as venting caps may not be enough to control bulging. But the bulging problem is particularly acute with closures which are substantially air tight. Thus the present invention finds a preferred application when using air tight closures. Preferably the containers herein are reclosable, and a suitable closure for this purpose is a conventional cap having a screw thread on the inside which corresponds with a screw thread on a portion of the container.

    [0012] Also included herein are deformable containers which are closed by a seal, i.e. containers which have no cap. Such containers are typically designed for a single use since they cannot be closed after they have been opened. Such containers, which are typically in the form of sachets or pouches, usually do not stand on a base, but bulging is still a problem in this case as it might cause said seal of said pouch to rupture under pressure.

    [0013] The container herein must be deformable. Indeed, if it is not deformable under the pressure generated inside it, then the bulging problem does not exist. Accordingly, such containers as glass containers are not included herein because they do not deform under internal pressure, even when they are closed. Containers made of thin metal material like Aluminium sheets can bulge and are therefore included herein. But the most commonly used deformable materials for making containers, especially bottles are thermoplastic materials, and thermoplastic materials are deformable under internal pressure even when fairly thick materials are used. Furthermore, a trend in today's packaging is clearly towards the use of so-called lightweight thermoplastic packages, i.e. made of very thin thermoplastic materials typically between 0.1 mm and 0.2 mm thick for pouches and between 0.5 mm to 2 mm for bottles, preferably 0.5 mm to 2 mm. These thin thermoplastic materials are of course very deformable and thus it becomes highly relevant to prevent bulging in these containers. Thermoplastic materials suitable for use herein include virgin and recycled materials and mixtures thereof, vinyl chloride based resins, polymers and copolymers derived from olefins, acrylic polymers and copolymers, polyethylene, polypropylene, polystyrene, polyethylene terephthalate, or mixtures thereof. It is important and well known in the art that compositions comprising peroxygen bleaches must be protected from UV and visible light in order to prevent decomposition as much as possible. This is typically ensured by using appropriate pigments, so-called masterbatches, in said thermoplastic materials. Thermoplastic materials for use herein can be single layer or multilayer materials.

    [0014] A second essential element of the present invention is the liquid bleach composition contained in the closed deformable container. The composition herein is an aqueous composition which comprises a peroxygen bleach or mixtures thereof, preferably hydrogen peroxide. Compositions herein include simple bleaching compositions as well as fully formulated consumer products which typically comprise other ingredients such as surfactants, solvents, chelants, polymers and the like.

    [0015] A first essential element in the compositions herein is the peroxygen bleach. Apparently the bulging problem comes from the reaction of oxygen with metal ions and radicals in the composition, which generates gas. Thus said reaction is likely to happen as soon as there is oxygen in the composition. Accordingly, the compositions herein may comprise any peroxygen bleach capable of yielding oxygen in the composition. This includes alkali metal peroxides, organic peroxides such as urea peroxide, preformed peracids such as nonylamide peroxyadipic acid, inorganic persalts such as perborates, percarbonates and the like. All of these eventually yield hydrogen peroxide, thus oxygen in the composition. The compositions according to the present invention may comprise from 0.5% to 30% by weight of the total composition, preferably from 1% to 15%, most preferably 3% to 10%, particularly if hydrogen peroxide is used.

    [0016] An essential element of the composition in the present invention is the presence of dipicolinic acid. Indeed, we have found that the presence of dipicolinic acid prevents the bulging of the container containing the composition. The desirable amount of dipicolinic acid is depending on various factors such as the specific container used and the specific formulation used, but it can be determined by simple trial and error.

    [0017] Preferably though, the composition herein should comprise dipicolinic acid in a weight ratio of bleach, particularly hydrogen peroxide, to dipicolinic acid of from 1550:1 to 1.4:1, preferably 1000:1 to 1.4:1 and more preferably 800:1 to 10:1. Other known peroxygen stabilizers, including butyl hydroxy toluene, etidronic acid, diethylene triamine penta methylene phosphonic acid (DTPA), benzoic acid and ethylene diamine-N,N'-disuccinic acid do not provide the anti bulging benefit, even at higher levels.

    [0018] It is preferable that the compositions herein be formulated at a pH of from 1 to 6, preferably 2 to 5. Indeed, we speculate that the pH of the composition might affect the DPA's ability to prevent bulging.

    [0019] Apart from water, hydrogen peroxide and dipicolinic acid, the compositions herein may comprise a variety of optional ingredients such as H2O2 stabilizers such as radical scavengers and chelants, surfactants, solvents, polymers, perfumes, dyes and the like.

    [0020] Suitable method for the determination of DPA present in the compositions according to the present invention is a potentiometric titration with CU(NO3)2 using a cupric electrode (Orion model 94-29®). Indeed, in said method 10 g. of a composition according to the present invention are weighted in a titration beaker. Then about 30 mL of buffer solution

    is added. Then a potentiometric titration is carried out, using a cupric electrode, with Cu(NO₃)₂ 0.01 N. However, before starting the titration, a stirage of about 80 seconds in order to equilibrate the electrode in the sample solution takes place. The increments of titrant to add should be maximum 0.01 mL and minimum 0.005 mL.

    [0021] The Cu(NO₃)₂ 0.01 N solution is standardized according to the following procedure: a 1N NaOH solution is added dropwise to 50 mL Cu(NO₃)₂ 0.01 N and 25 mL deionised water still a slight precipitate occurs, then 4.5 mL glacial acetic acid and about 2 g of potassium iodide crystals are added. A dark brown color will appear. Then a titration with sodium thiosulphate 0.1 N (analytical reagent grade) until yellow color should immediately be carried out. Then a knife-tip of soluble starch is added to Zulkowsky and the titration is continued until the last blue color has disappeared. This standardization is repeated three times.

    .

    [0022] The percentage of DPA present in a given composition according to the present invention is given by the following formula:



    [0023] The present invention is further illustrated by the following examples and experiments.

    Examples and Experiments



    [0024] Compositions 1 to 6 were made as indicated (in weight %) and then used to fill identical containers. The containers used were with HDPE with 4% masterbatch. The bottles were 1 Lit. Bottles, about 280mm high, about 120mm deep and 65mm wide. The thickness of the walls of the bottles ranged from 0.7mm to 1.6mm. Containers were closed with an air tight cap with a screw thread. To ensure air tightness during the test, silicone bands were added on the threads and caps were sealed with a tape. The filled and closed containers were then stored at 50°c for the indicated periods. The results are shown at the bottom of the table (B stands for bulged, SB stands for slightly bulged, NB stands for not bulged). Also the available oxygen loss is measured for information purposes, and expressed as a % loss over the listed period.
    1 2 3 4 5 6
    H2O2 7 7 7 7 7 7
    Alkyl sulfate 1 1 1 1 1 1
    Nonionic surfactant (Ukanil®) 1 1 1 1 1 1
    Butyl hydroxy toluene 0.03 0.03 0 0.03 0.03 0.03
    Dipicolinic acid 0 0.08 0 0 0 0.01
    Etidronic acid 0 0 0.44 0 0 0
    DTPA 0 0 0 0.1 0 0
    Benzoic acid 0 0 0 0 0.08 0
    pH 4 4 4 4 4 4
    Water and minors -------------------------up to 100%------------------
    Bulging results:            
    2 days storage NB NB NB NB NB NB
    4 days storage B NB SB SB NB NB
    6 days storage B NB B B B NB
    8 days storage B NB B B B NB
    (% H2O2 loss) 1.2 0.5 0.47 0.6 N/A N/A


    [0025] These results clearly show that in the experiment with compositions 2 and 6, according to the present invention, bulging is prevented. In contrast, with all other experimental conditions, i.e. compositions 1,3 and 4, bulging eventually occurs as soon as 6 days storage. Remarkably, bulging is prevented in experiment 2, whereas in experiments 3 and 4 bulging occurs although the available oxygen loss is similar and even less than in composition 2.

    [0026] Other examples of the present invention were formulated as follows (weight %) in the same containers as above.
    H2O2 7%
    Dobanol ® 91/10 2.6%
    Dobanol ® 23-6.5 0.9%
    Dobanol ® 23-3 1.0%
    Lutensol ® AO 30 0.75%
    ISOFOL 16 0.2%
    DPA 0.02%
    BHT 0.03%
    pH 4
    Water and minors up to 100%
    Hydrogen peroxide 7.0%
    Alkyl sulfate 1.0%
    Ukanil ® 1.0%
    BHT 0.03%
    DPA 0.02%
    pH 4
    Water and minors up to 100%
    H2O2 7%
    Dobanol ® 23-6.5 0.9%
    Alkylsulfate 1.0%
    Lutensol ® AO 3109 3.5%
    ISOFOL 16 0.2%
    DPA 0.04%
    BHT 0.03%
    pH 4
    Water and minors up to 100%
    H2O2 7%
    Dobanol ® 23-3 1.1%
    Alkylsulfate 1.5%
    Dobanol ® 91-10 1.6%
    ISOFOL 16 0.5%
    DPA 0.01%
    BHT 0.03%
    pH 4
    Water and minors up to 100%



    Claims

    1. A closed deformable container containing a liquid aqueous composition comprising a peroxygen bleach and an effective amount of dipicolinic acid.
     
    2. The use of dipicolinic acid, in a liquid aqueous bleach composition comprising hydrogen peroxide, to prevent the bulging of the deformable container containing said composition.
     
    3. A container or use according to claims 1 or 2 where said container is made of a thermoplastic material.
     
    4. A container or use according to the preceding claims wherein said container is closed in a substantially air-tight manner.
     
    5. A container or use according to any of the preceding claims wherein said peroxygen bleach is hydrogen peroxide.
     
    6. A container or use according to claim 5 wherein said composition comprises from 0.5% to 30% by weight of the total composition of hydrogen peroxide, preferably 1% to 15%, most preferably from 3% to 10%.
     
    7. A container or use according to the preceding claims wherein said composition comprises dipicolinic acid and a peroxygen bleach in a weight ratio of peroxygen bleach to dipicolinic acid of from 1550:1 to 1.4:1, preferably 1000:1 to 1.4:1 and more preferably from 800:1 to 10:1.
     
    8. A container or use according to the preceding claims wherein said composition is formulated at a pH ranging from 1 to 5.