EP1776291A1

EP1776291A1 - A package containing tablets

Info

Publication number: EP1776291A1
Application number: EP05749366A
Authority: EP
Inventors: Andrew John Unilever R & D Vlaardingen COLE; Roy Unilever R & D Vlaardingen VAN HEESEN
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2004-06-15
Filing date: 2005-05-20
Publication date: 2007-04-25
Also published as: GB0413327D0; WO2005123536A1

Abstract

A package (1) comprising a reclosable, container (3) having a base wall and at least four lateral walls for containing and supporting a plurality of tablets (5), each tablet (5) having at least one lateral face (7) and a diametrical fracture stress of between 15 and 65 kilo Pascal, wherein the package (1 ) further includes, in addition to the container (3 ), a removable shock absorbing means (9) comprising a flexible cushioning material which is resiliently deformable for absorbing shock to the tablets (5), the shock absorbing means (9) selectively positioned internally of the container (3) such that it is within a plane parallel to at least a portion of the lateral face of the tablets.

Description

A PACKAGE CONTAINING TABLETS

The invention relates to a package containing tablets, especially tablets for use with laundry, i.e. washing, treating clothes etc., and automatic dish-washing.

Tablets have several advantages over free-flowing powdered products, in particular, as they do not require measuring they are thus easier to handle and dispense into the wash load and allow for accurate dosing of detergent. A problem encountered with e.g. laundry tablets is that the tablets need to be strong enough to withstand storage, transport, yet weak enough to disintegrate and dissolve quickly in the wash liquor. Generally an increase in tablet strength is offset by an undesirable increase in disintegration time.

It is known to package such tablets in cartons which are formed from fluted or corrugated cardboard. However, paperboard may require the introduction of additional layers for moisture protection. Also such packaging is limited aesthetically, additional layers coloured paper, plastic, metal are needed to introduce superior graphics.

Furthermore, conventionally tablets are tightly packed within cartons to minimise damaging interactions which occur between adjacent tablets during transportation and handling. A consequence of such packing is that removal of a tablet (s) for use when the carton is first opened is awkward and difficult. This can cause damage to the structural integrity of the tablet due to the consumer grasping at it trying to remove it from the carton, therefore, resulting in an undesirable amount of premature disintegration.

An object of the invention is to eliminate or at least reduce the above problems by allowing the provision of an aesthetically pleasing package containing tablets which have satisfactory dissolution properties but which are also sufficiently strong to withstand transport, storage and handling without breaking.

Accordingly, the invention therefore provides a package containing tablets as defined in claim 1.

With this arrangement tablets having a density favouring satisfactory dissolution can be packaged in a container which can itself be designed without reference to cushioning properties since this is provided by the selectively positioned shock absorbing means. At the same time the shock absorbing means need not provide any support or containment of the tablets and have as its sole purpose, to absorb shock to the tablets. Hence the problems of shock absorbency and containment are decoupled. This means that the container can be made stronger and that aesthetic considerations of the container can take a higher priority.

Hence in a preferred embodiment the container is a rigid container and the shock absorbing means is a highly flexible cushioning material which is resiliently deformable. The term "resiliently deformable" means that the material will deform when pressure is applied thereto, but at the same time has adequate resilience to have a small amount of spring back. This combination of features provides an effective shock absorbing means.

Furthermore, as the shock absorbing means is a separate entity, it can be removed from the container once the consumer has purchased the container and it is placed on the consumer's shelf. The requirement for the shock absorbing means no longer exists at this time because the package is unlikely to be subject to any further significantly damaging disturbance. Removal of the shock absorbing means increases the available inner volume of the packaging, therefore, allowing effortless removal of the tablets for use.

In a preferred embodiment of the present invention the shock absorbing means is parallel with one or more of the lateral wall of the container.

It is preferably that the shock absorbing means is parallel to and extends across the lateral walls rather than the base wall of the container. This is because the tablets are positioned in the container such that their lateral sides contact the lateral walls of the tub. In the case of tablets with curved lateral walls e.g. cylindrical tablets, it is these areas of the tablet through which the greatest (due to the small area) forces from shock are transmitted and where the tablet is therefore most vulnerable. Therefore, as these areas of the tablet (s) do not contact the base wall of the container there is no need for the shock absorbing means to be positioned in the base. This provides a further advantage of the present invention by reducing the cost of the shock absorbing means, financially and environmentally.

Accordingly, in a preferred embodiment of the present invention the shock absorbing means extends across at least one lateral wall of the container , more preferably at least two lateral walls, more preferably at least three lateral walls and most preferably at least four lateral walls of the container.

The shock absorbing means may have a flat crushability in the range 50-800 Kilo Pascal. The flat crush- ability corresponds to the largest force per unit area that the material can resist without being completely crushed, the force being applied along a direction normal to the surface of the material. It is measured using a Flat Crush Test, or FCT. Furthermore, it was found that a packaging system having a low flat crush-ability could not absorb the energy of a chock sufficiently to prevent breaking the tablets, while a high flat crush-ability would render the packaging material too rigid, so that the energy of a chock would not be absorbed either but transmitted to the tablets.

In a particular preferred embodiment both the container and the shock absorbing means are transparent and uses air cushioning e.g. air cellular cushioning as the shock absorbing means.

The air cellular cushioning preferably comprises air cells with a height in the range of 0.1cm - 1cm and preferably

0.15 - 0.8cm and further preferably 0.3 - O.βcm. This range of bubble height protects the tablets without significantly reducing the available volume in the container for storing tablets. At same time, removal of cushioning of this depth increases the inner volume sufficiently to allow easy retrieval of tablets.

Accordingly, the container may be a rigid thermoformed or injection moulded plastic tub.

The combination of a transparent container and shock absorbing means allow consumers to view the tablets before purchase, whilst within the closed pack. This can be advantageous if, for example the tablets comprise visual cues (colouring, patterns etc) . This is difficult to achieve if a non-transparent container is used to provide the cushioning.

A "tablet" as used herein is meant to mean a block of material, having a longitudinal axis, and a height along the longitudinal axis to provide a lateral face or faces. It may have a substantially constant cross section in a plane normal to the longitudinal axis. The cross section can take various shapes including a circle, an ellipse, a square, a rectangle or other polygons for example. Edges may be chamfered or rounded to avoid mechanical weakness.

The surface of the section of a tablet may be between 500 and 2000 mm², preferably between 1000 and 1800 mm², more preferably between 1200 and 1600 mm². In a preferred embodiment, the tablet has a circular section having a 45 mm diameter. Typically, the height of a tablet along the longitudinal axis is comprised between 10 and 30 mm, preferably between 15 and 25 mm. In one example the tablet has a disc shape and has a circular section having a 45mm radius, 16mm height, and a single curved lateral face.

The diametrical fracture stress (as a measure of strength) of the tablet should not be too low as it would be very fragile and difficult to handle, and it should not be too high as the tablet would be too solid and would therefore have difficulties to dissolve.

The diametrical fracture stress of the tablet is measured by applying a force onto the side of the tablet (where it is found to be weakest) in a direction normal to the longitudinal axis of the tablet up to cracking of the tablet. Such a test can be applied to various cross section of tablets, including circular for example. The diametrical fracture stress of the tablet is linked to the compression strength used for forming of the tablet. The higher the compression, the higher will be the diametrical fracture stress.

It is preferred to use a tablet having a diametrical fracture stress comprised between 18 and 45 kilo Pascal, and more preferably between 20 and 25 kilo Pascal.

A tablet of this invention intended for fabric washing will be likely to contain at least 2 wt%, probably at least 5 wt%, up to 40 or 50 wt% surfactant based on the whole tablet, and from 5 to 80 wt% detergency builder, based on the whole tablet.

Materials which may be used in laundry tablets of this invention will now be discussed in more detail.

Surfactant Compounds

Compositions which are used in tablets of the invention will contain one or more detergent surfactants. In a fabric washing composition, these preferably provide from 5 to 50% by weight of the overall tablet composition, more preferably from 8 or 9% by weight of the overall composition up to 40% or 50% by weight. Surfactant may be anionic (soap or non- soap) , cationic, zwitterionic, amphoteric, nonionic or a combination of these.

Anionic surfactant may be present in an amount from 0.5 to 50% by weight, preferably from 2% or 4% up to 30% or 40% by weight of the tablet composition.

Synthetic (i.e. non-soap) anionic surfactants are well known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly sodium linear alkylbenzene sulphonates having an alkyl chain length of Cs-Cis; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.

Primary alkyl sulphate having the formula ROS0₃ ^" M⁺ in which R is an alkyl or alkenyl chain of 8 to 18 carbon atoms especially 10 to 14 carbon atoms and M⁺ is a solubilising cation, is commercially significant as an anionic surfactant. Linear alkyl benzene sulphonate of the formula

where R is linear alkyl of 8 to 15 carbon atoms and M⁺ is a solubilising cation, especially sodium, is also a commercially significant anionic surfactant.

Frequently, such linear alkyl benzene sulphonate or primary alkyl sulphate of the formula above, or a mixture thereof will be the desired anionic surfactant and may provide 75 to 100 wt% of any anionic non-soap surfactant in the composition.

In some forms of this invention the amount of non-soap anionic surfactant lies in a range from 5 to 20 wt% of the tablet composition.

It may also be desirable to include one or more soaps of fatty acids. These are preferably sodium soaps derived from naturally occurring fatty acids, for example, the fatty acids from coconut oil, beef tallow, sunflower or hardened rapeseed oil.

Suitable nonionic surfactant compounds which may be used include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide.

Specific nonionic surfactant compounds are alkyl (C₈-₂₂) phenol-ethylene oxide condensates, the condensation products of linear or branched aliphatic C₈-₂o primary or secondary alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylene-diamine.

Especially preferred are the primary and secondary alcohol ethoxylates, especially the C₉-n and Cι₂_ι₅ primary and secondary alcohols ethoxylated with an average of from 5 to 20 moles of ethylene oxide per mole of alcohol.

In some fabric washing tablets of this invention, the amount of nonionic surfactant lies in a range from 4 to 40%, better 4 or 5 to 30% by weight of the whole tablet.

Many nonionic surfactants are liquids. These may be absorbed onto particles of the composition.

Detergency Builder

A composition which is used in tablets of the invention will contain from 5 to 80%, more usually 15 to 60% by weight of detergency builder. This may be provided wholly by water soluble materials, or may be provided in large part or even entirely by water-insoluble material with water-softening properties. Water-insoluble detergency builder may be present as 5 to 80 wt%, better 5 to 60 wt% of the composition. Alkali metal aluminosilicates are strongly favoured as environmentally acceptable water-insoluble builders for fabric washing. Alkali metal (preferably sodium) aluminosilicates may be either crystalline or amorphous or mixtures thereof, having the general formula: 0.8 - 1.5 Na₂O.Al₂0₃. 0.8 - 6 Si0₂. xH₂0

These materials contain some bound water (indicated as AxH20≤) and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates contain 1.5-3.5 Si0₂ units (in the formula above) . Both the amorphous and the crystalline materials can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature.

Suitable crystalline sodium aluminosilicate ion-exchange detergency builders are described, for example, in GB 1429143 (Procter & Gamble) . The preferred sodium aluminosilicates of this type are the well known commercially available zeolites A and X, the novel zeolite P described and claimed in EP 384070 (Unilever) and mixtures thereof.

Conceivably a water-insoluble detergency builder could be a layered sodium silicate as described in US 4664839.

NaSKS-6 is the trademark for a crystalline layered silicate marketed by Hoechst (commonly abbreviated as ASKS-6"). NaSKS-6 has the delta-Na₂SiOs morphology form of layered silicate. It can be prepared by methods such as described in DE-A-3,417, 649 and DE-A-3, 742, 043. Other such layered silicates, such as those having the general formula NaMSi_x0_2x+ι. yH₂0 wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used.

Water-soluble phosphorous-containing inorganic detergency builders, include the alkali-metal orthophosphates, metaphosphates, pyrophosphates and polyphosphates . Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates .

Non-phosphorous water-soluble builders may be organic or inorganic. Inorganic builders that may be present include alkali metal (generally sodium) carbonate; while organic builders include polycarboxylate polymers, such as polyacrylates, acrylic/ aleic copolymers, and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates .

At least one region (preferably the second region) of a fabric washing tablet preferably include polycarboxylate polymers, more especially polyacrylates and acrylic/maleic copolymers which can function as builders and also inhibit unwanted deposition onto fabric from the wash liquor.

Bleach System

Tablets according to the invention may contain a bleach system in at least one region of a tablet, preferably in the second region. This preferably comprises one or more peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, which may be employed in conjunction with activators to improve bleaching action at low wash temperatures. If any peroxygen compound is present, the amount is likely to lie in a range from 10 to 25% by weight of the composition.

Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, advantageously employed together with an activator. Bleach activators, also referred to as bleach precursors, have been widely disclosed in the art. Preferred examples include peracetic acid precursors, for example, tetraacetylethylene diamine (TAED) , now in widespread commercial use in conjunction with sodium perborate; and perbenzoic acid precursors. The quaternary ammonium and phosphonium bleach activators disclosed in US 4751015 and US 4818426 (Lever Brothers Company) are also of interest. Another type of bleach activator which may be used, but which is not a bleach precursor, is a transition metal catalyst as disclosed in EP-A-458397, EP-A-458398 and EP-A-549272. A bleach system may also include a bleach stabiliser (heavy metal sequestrant) such as ethylenediamine tetramethylene phosphonate and diethylenetriamine pentamethylene phosphonate.

As indicated above, if a bleach is present and is a water- soluble inorganic peroxygen bleach, the amount may well be from 10% to 25% by weight of the composition. Other Detergent Ingredients

The detergent tablets of the invention may also contain one of the detergency enzymes well known in the art for their ability to degrade and aid in the removal of various soils and stains. Suitable enzymes include the various proteases, cellulases, upases_/ amylases, and mixtures thereof, which are designed to remove a variety of soils and stains from fabrics. Examples of suitable proteases are Maxatase (Trade Mark), as supplied by Gist-Brocades N.V., Delft, Holland, and Alcalase (Trade Mark) , and Savinase (Trade Mark) , as supplied by Novo Industri A/S, Copenhagen, Denmark. Detergency enzymes are commonly employed in the form of granules or marumes, optionally with a protective coating, in amount of from about 0.1% to about 3.0% by weight of the composition; and these granules or marumes present no problems with respect to compaction to form a tablet.

The detergent tablets of the invention may also contain a fluorescer (optical brightener) , for example, Tinopal (Trade Mark) DMS or Tinopal CBS available from Ciba-Geigy AG,

Basel, Switzerland. Tinopal DMS is disodium 4, 4 'bis- (2- morpholino-4-anilino-s-triazin-6-ylamino) stilbene disulphonate; and Tinopal CBS is disodium 2, 2 ' -bis- (phenyl- styryl) disulphonate.

An antifoam material is advantageously included especially if a detergent tablet is primarily intended for use in front-loading drum-type automatic washing machines. Suitable antifoam materials are usually in granular form, such as those described in EP 266863A (Unilever) . Such antifoam granules typically comprise a mixture of silicone oil, petroleum jelly, hydrophobic silica and alkyl phosphate as antifoam active material, absorbed onto a porous absorbed water-soluble carbonate-based inorganic carrier material. Antifoam granules may be present in an amount up to 5% by weight of the composition.

It may also be desirable that a detergent tablet of the invention includes an amount of an alkali metal silicate, particularly sodium ortho-, meta- or disilicate. The presence of such alkali metal silicates at levels, for example, of 0.1 to 10 wt%, may be advantageous in providing protection against the corrosion of metal parts in washing machines, besides providing some measure of building and giving processing benefits in manufacture of the particulate material which is compacted into tablets.

A tablet for fabric washing will generally not contain more than 15 wt% silicate. A tablet for machine dishwashing will often contain more than 20 wt% silicate. Preferably the silicate is present in the second region of the tablet.

Further ingredients which can optionally be employed in a region of a fabric washing detergent of the invention tablet (preferably the second region) include anti-redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, fabric- softening agents; heavy metal sequestrants such as EDTA; perfumes; and colorants or coloured speckles. Tableting machinery able to carry out the manufacture of tablets of the invention is known, for example suitable tablet presses are available from Fette and from Korch. Tableting may be carried out at ambient temperature or at a temperature above ambient which may allow adequate strength to be achieved with less applied pressure during compaction. In order to carry out the tableting at a temperature which is above ambient, the particulate composition is preferably supplied to the tableting machinery at an elevated temperature. This will of course supply heat to the tableting machinery, but the machinery may be heated in some other way also.

Since the tablet was found to be more fragile when hit on the side, the shock absorbing means is targeted to protect this area.

Such a selection of the location allows to save materials as the container to be made from materials which have very little shock absorbing properties but which are e.g. rigid, strong, and/or aesthetically very pleasing.

A non-limiting example of the invention is now described in detail with reference to the following drawing:

Figure 1 is a perspective view of a package according to one embodiment of the invention.

In the example, the package 1 was comprising the combination of a reclosable container 3 comprising a thermoformed

•polystyrene tub 3. The container 3 has a base wall 13 a lid 11 opposite the base wall, and four lateral walls 15 and contains a plurality of laundry detergent tablets 5. Each tablet 5 is disc shaped having and a height along its longitudinal axis to provide a lateral face 7 and a constant circular cross section.

The tablet has the following formulation: -

A detergent powder was made of the following composition by pregranulating the granule ingredients, followed by post-dosing the rest of the ingredients

25 grammes of the powder are inserted into a 45 mm die of a tabletting machine, optionally followed by a flattening step. The material is compressed at 6 KN/cm² into a single tablet, followed by ejection of the tablet. The tablet has a diametrical fracture stress of between 15 and 65 kilo Pascal.

The package 3 further includes, in addition to the plastic tub 1, a removable shock absorbing means 9 comprising a sheet of five layers of transparent air cellular cushioning comprising Bubble Wrap® for absorbing lateral shock to the tablets 5.

The tablets are arranged as flow wrapped pairs (flow wrapping not shown) , where in each pair the tablets 5 are side by side in the container such that their longitudinal axis are aligned. Due the circular cross section of the tablets, they can only contact each other laterally at longitudinal sections of their lateral faces. Each tablet also has second diametrically opposed longitudinal section which can contact the lateral wall of the tub. It is these areas of the tablet through which the greatest (due to the small area) forces from shock are transmitted and where the tablet is therefore most vulnerable.

The shock absorbing Bubble Wrap® 9 is selectively positioned internally of the container 3 such that it is restricted to lie only within a plane parallel to these longitudinal sections. This is achieved by having the Bubble Wrap® 9 removably attached e.g. by a small patch of adhesive to the inner face of the four lateral walls of the tub 1. Alternatively the shock absorbing Bubble Wrap® may be packed without any fixing and retained in place by the tablets themselves. There is no bubble wrap in the base. This reduces the cost of the shock absorbing means, financially and environmentally.

The shock absorbing Bubble Wrap® 9 has a bubble height of 3 0.48cm ( /i6 inch) and a relatively low flat crushability within the range 50 - 800 Kilo Pascal. The tub is rigid and has a very high flat crushability, exceeding the range of Bubble Wrap®.

The polystyrene tub is transparent and coloured to present an aesthetically pleasing and re-usable package. The transparency of the container and the shock absorbing means allows consumers to view the tablets before purchase, without opening the package.

In this manner, both the protection and the aesthetic appeal of the packaged tablets is ensured. In drop tests made with a full box from a 50 cm height and with the side of the tablets facing the ground, i.e. with the longitudinal axis of the tablets being horizontal as on the Figures, the level of tablet integrity was significant.

It should be mentioned that the plastic flow wrap is not shown on the drawings for clarifying the other elements.

Claims

1. A package (1) comprising a reclosable, container (3) having a base wall and at least four lateral walls for containing and supporting a plurality of tablets (5) , each tablet (5) having at least one lateral face (7) and a diametrical fracture stress of between 15 and 65 kilo Pascal, wherein the package (1 ) further includes, in addition to the container (3 ), a removable shock absorbing means (9) comprising a flexible cushioning material which is resiliently deformable for absorbing shock to the tablets (5) , the shock absorbing means (9) selectively positioned internally of the container (3) such that it is within a plane parallel to at least a portion of the lateral face of the tablets.

2. A package (1) according to claim 2, wherein the shock absorbing means (9) is substantially parallel with one or more of the lateral walls of the container and substantially perpendicular to the base wall.

3. A package (1) according to any preceding claim wherein the shock absorbing means (9) extends across at least one lateral wall of the container (3) .

A package (1) according to claim 3 wherein the shock absorbing means (9) extends across at least two lateral walls .

5. A package (1) according to claim 3 wherein the shock absorbing means (9) extends across at least three lateral walls .

6. A package (1) according to claim 3 wherein the shock absorbing means (9) extends across all four lateral walls .

7. A package (1) according to any preceding claim wherein the shock absorbing means (9) has a flat crushability between 50 and 800 Kilo Pascal.

8. A package (1) according to any preceding claim wherein the shock absorbing means (9) is selected from the group consisting of foam and/or air cellular cushioning material.

9. A package (1) according to claim 2, wherein the tablets (3) are arranged in the container side by side such that their longitudinal axis substantially parallel.

10. A package (1) according to any. preceding claim, wherein the container is a rigid thermoformed or injection moulded plastic tub.

11. A package (1) according to any preceding claim, wherein the container and the shock absorbing means are transparent or translucent.

2. A packaged product (1) according to claim 1, whereby the tablet (20) is a laundry treatment or automatic detergent tablet.