[0001] This invention relates to cleaning compositions in the form of tablets for example,
for use in fabric washing or machine dishwashing.
[0002] Detergent compositions in tablet form have advantages over powdered products in that
they do not require measuring and are thus easier to handle and dispense into the
washload.
[0003] It is desirable that detergent tablets have sufficient strength to keep them intact
during storage and handling prior to use but also disintegrate rapidly when in contact
with a limited amount of water.
[0004] Strength when dry and rapid disintegration when wet are desirable properties which
militate against each other. When tablets are made by compacting a composition in
particulate form, the force used for compaction affects these two properties.
[0005] Tablets formed using a low compaction pressure tend to crumble and disintegrate on
handling and packing; while more forcefully compacted tablets may be sufficiently
cohesive but can be slow to disintegrate or disperse to an adequate extent in use.
[0006] It has been described in EP 716 144 to use an organic polymeric binder material to
enhance the strength of detergent tablets. However the use of such binder materials
may undesirably increase the costs and also may lead to a more complicated process
for manufacturing the tablets.
[0007] Also it has been suggested that if a tablet contains organic surfactant, this can
function as a binder, plasticising the tablet. However the presence of the surfactants
may sometimes retard disintegration of the tablet by forming a viscous gel when the
tablet comes into contact with water. Thus, the presence of surfactant can make it
more difficult to achieve good disintegration while maintaining adequate strength.
[0008] The object of the present invention is to provide detergent tablets comprising one
or more phases of compacted particulate material and one or more smooth phases wherein
said phase(s) does not require very high compaction pressures to ensure adequate strength
for the tablet, and wherein the use of binder materials can be avoided.
[0009] It has now been found that a detergent tablet wherein the tablet comprise a first
phase composed of a compacted particulate material, wherein said first phase comprises
phosphate builder having a water content of from 5.5 to 22.7 wt% (based on the weight
of the phosphate builder) and wherein at least 40% of said phosphate builder is in
Phase I form, and a second phase which is a smooth phase, provides good dispersing
and cleaning properties and said detergent tablet has a good strength.
[0010] Accordingly in a first aspect the present invention relates to a detergent tablet
wherein the tablet comprises a first phase and a second phase, wherein said first
phase comprises a compacted particulate material and wherein said first phase comprises
phosphate builder having an average water content of from 5.5 to 22.7 wt% and wherein
at least 40 wt% of said phosphate builder in said first phase is in Phase I form,
and wherein said second phase is a smooth phase.
[0011] Some prior disclosures describe the use phosphate builders in cleaning tablets, for
example EP 839 906 discloses the use in tablets of sodium tripolyphosphate containing
between 1.0 and 5.0 wt% of water of hydration. WO 00/22090 discloses a anti-calcium
tablets comprising a phosphate builder with 6 to 16 wt% of water. WO 02/42398 discloses
detergent tablets comprising sodium tripolyphosphate which may comprise hydration
levels of from 0.5 to 10 wt%. WO 00/32741 discloses detergent tablets comprising partially
hydrated sodium tripolyphosphate.
[0012] EP 1239028 describes the production of multi-layer detergent tablets wherein partially
hydrated sodium tripolyphosphate having up to 5% of water of hydration.
[0013] WO 00/12671 discloses a detergent tablet with a sodium tripolyphosphate builder which
is a mixture of sodium tripolyphosphate hexahydrate, 1-18% Phase I anhydrous sodium
tripolyphosphate and Phase II anhydrous sodium tripolyphosphate.
[0014] Preferably tablets of the invention are of cylindrical shape wherein the two main
surfaces (upper side and bottom side) are substantially flat.
[0015] As indicated above, the invention relates to a multiphase tablet wherein a compacted
particulate phase and a smooth phase are present and optionally one or more other
smooth or compacted particulate phase(s) are present. Especially preferably tablets
of the inventions comprise a limited number of compacted phases (up to 5, preferably
one compacted phase) in combination with a limited number of smooth phases (up to
5, preferably one smooth phase).
[0016] The regions of a multi-phase tablet are possibly separate layers within a tablet.
However, a discrete region of a tablet could also have other forms for example one
or more core(s) or insert(s). In a preferred embodiment the first region is a layer
of compacted particulate material and the second region is a smooth layer. In a further
advantageous embodiment the first region is a core or insert of e.g. a smooth material
embedded in the second region which is for example a layer of compacted particulate
material.
[0017] The multi-phase tablet comprises a compacted phase preferably having a weight of
from 2 to 50 grammes, more preferred from 3 to 40 grammes. Preferably the other phases
together including one or more smooth phases have a weight of 10 to 50 grammes, more
preferred 15 to 40 grammes, whereby each phase has a weight of from 2 to 50 grammes,
more preferred from 3 to 40 grammes.
[0018] In a preferred embodiment of the invention the compacted particulate phase as described
above comprises no or only low levels of surfactants. Preferably the level of surfactants
in the compacted particulate phase is less than 10 wt% (based on the total weight
of said phase), more preferred from 0 to 9 wt%, most preferred from 1 to 8 wt%. It
has been found that the absence of high levels of surfactants -which normally would
act as a binder- in the compacted particulate phase does not lead to unacceptable
low coherence between the particulates, provided the compacted particulate phase comprises
a phosphate builder having a water content between 5.5 and 22.7 % based on the weight
of the phosphate builder.
[0019] Preferably the level of phosphate builder having a water content between 5.5 and
22.7 % in the compacted particulate phase is from 10 to 90 wt%, more preferred from
15 to 80 wt%, most preferred from 20 to 70 wt% based on the total weight of the compacted
phase. If desired a mixture of phosphate builders may be used, provided that the average
degree of hydration of the phosphate builder is at within the ranges as described
herein. Preferably the phosphate builder is STP. Generally the moisture in the phosphate
builder will be present as crystal water. The upper limit for the moisture level of
the phosphate builder is 22.7 wt%, referring to the fully hydrated STP hexahydrate
state. Preferably the average water content is at least 7.5 wt% (based on the total
amount of phosphate present in the compacted phase), more preferred more than 10 wt%
preferably up to 20 wt%.
[0020] Preferably the phosphate builder is for at least 50% by weight in the Phase I form.
[0021] In a preferred embodiment of the invention the detergent tablets comprise a silicate.
Especially preferable the level of silicate (preferably in the form of alkali metal
silicate) is from 1 to 15 wt% based on the weight of the phosphate builder, more preferred
from 2 to 12 wt%, most preferred from 4 to 8 wt%. Preferably the silicate is present
in the same phase of the tablet as the phosphate builder.
[0022] Although the compacted particulate region may comprise some surfactant materials,
this region preferably comprises ingredients of the tablet other than surfactants.
Examples of these ingredients are for example builders, bleach system, enzymes etc.
Preferably the builders in the tablet are predominantly present in the compacted particulate
region (s). Also preferably the bleach system is predominantly present in the compacted
particulate region. Also preferably the enzymes are predominantly present in the compacted
particulate region. For the purpose of this invention, unless stated otherwise, the
term "predominantly present" refers to a situation wherein at least 90 wt% of an ingredient
is present in the compacted particulate region, more preferred more than 98 wt%, most
preferred substantially 100 wt%.
[0023] The invention relates to the combination of at least one compacted particulate phase
and at least one smooth phase. For the purpose of this invention the term smooth phase
refers to compositions which are on the one hand solid enough to retain their shape
at ambient temperature and on the other hand smooth in appearance. Smooth textures
are generally of low or no porosity and have -at normal viewing distance- the appearance
of a continuous phase for example as opposed to porous and particulate appearance
of a compacted particulate material.
[0024] In an advantageous embodiment of the invention the smooth phase comprises from 20-80
wt% of non-soap surfactants (based on the total weight of said smooth phase), more
preferred from 25 to 75 wt%, most preferred 30 to 70 wt%. It has been found that the
combination of a separate smooth second region and these high surfactant levels provide
very good dispersing and cleaning properties to the tablet.
[0025] Preferably the non-soap surfactants in the smooth region comprise a combination of
anionic surfactants and non-ionic surfactants in a weight ratio of from 5 : 1 to 1
: 5, more preferred 3 : 1 to 1 : 3, more preferred 2 : 1 to 1: 2. Further surfactants,
for example cationic surfactants may equally be present for example at a level of
0.1 to 10 wt% based on the weight of the smooth part.
[0026] The smooth region may also contain structuring materials which leads on the one hand
to a desired firm consistency of the smooth phase but on the other hand retains the
smooth nature of the phase. Examples of such structuring materials are for example
soap, urea, acetate, sugar etc. Preferably the level of structurant materials is from
0.5 to 40 wt% based on the total weight of the smooth phase.
[0027] The smooth region of the tablet may also contain diluent materials for example polyethyleneglycol,
dipropyleneglycol, isopropanol or (mono-)propyleneglycol. Preferable the level of
these diluents is from 0 to 40 wt%, more preferred 1 to 20, most preferred from 4
to 15 wt% based on the weight of the smooth phase.
[0028] The smooth phase comprises no or only low levels of water. Preferably the level of
water is less than 20 wt % based on the weight of the smooth phase, more preferred
less than 15 wt%, most preferred from 5 to 12 wt%. Most preferably the smooth phases
are substantially free from water, which means that apart from low levels of moisture
(e.g. for neutralisation or as crystal water) no additional added water is present.
[0029] Preferably the total weight of surfactants in the smooth phase is from 2 to 20 grammes,
more preferred from 3 to 10 grammes.
[0030] Preferably the smooth phase comprises no or only low levels of ingredients such as
builders, bleach activators and bleach materials. Preferably the level of these ingredients
in the smooth phase is less than 5 wt%.
[0031] The above description of the tablet has been given with reference to a tablet constituted
by two regions. It will however be understood that each of the regions may be composed
of a limited number of discrete regions. In addition to the regions described above,
tablets of the invention may optionally comprise further regions, for example the
tablet may be partially or wholly coated.
[0032] The compacted particulate phase of the cleaning tablets according to the invention
is preferably manufactured by introducing a particulate material into a tablet mould
followed by compaction. Generally compaction pressures will be typically be in the
range of from 0.05 to 5 kN/cm
2 . Due to the fact that the hydrated phosphate builder acts as a binder, generally
the compaction pressure may be relatively low. If the cleaning tablet of the invention
comprises more than one compacted particulate phase, this may be prepared by consecutive
compression steps such as for example described in EP 1239028. The smooth phases could
for example be prepared by heating of the ingredients followed by cooling, casting
and/or by extrusion. The smooth parts can then for example be adhered to the compacted
phase by co-compression.
[0033] Preferably the (co-)compression of the combination of the smooth and the compacted
region(s) takes place at a force of from 0.05 to 20 kN/cm
2. Especially if the solid region has been pre-compressed the co-compression in step
advantageously be at a force of 0.1- 10 kN/cm
2, more preferred 0.5 to 5 kN/cm
2. Such co-compression generally leads to good adherence of the first region to the
second region and avoids the need of applying an adhesive material between the smooth
and solid region. Another advantage of the method of the invention is that it can
be carried out in a normal tablet press without the need of adaptation of the shape
of the pressing surfaces.
[0034] A tablet of this invention may be intended for use in machine dishwashing. Such a
tablet is likely to contain surfactant in a low concentration such as 0.5 to 2 wt%
based on the whole tablet, although higher concentrations ranging up to 10 wt% may
be used. Such will typically contain salts, such as over 60 wt%, often over 85 wt%
of the tablet.
[0035] Water soluble salts typically used in machine dishwashing compositions are phosphates
(including condensed phosphates) carbonates and silicates, generally as alkali metal
salts. Water soluble alkali metal salts selected from phosphates, carbonates and silicates
may provide 60 wt% or more of a dishwashing composition.
[0036] Another preferred possibility is that a tablet of this invention will be intended
for fabric washing. In this event the tablet will be likely to contain at least 2
wt%, probably at least 5 wt%, up to 40 or 50 wt% non-soap surfactant based on the
whole tablet, and from 5 to 80 wt% detergency builder, based on the whole tablet.
[0037] Materials which may be used in tablets of this invention will now be discussed in
more detail.
Surfactant Compounds
[0038] 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.
[0039] 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.
[0040] 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 C
8-C
15; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid
ester sulphonates.
[0041] Primary alkyl sulphate having the formula
ROSO
3- 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] Soaps for use in accordance to the invention are preferably sodium soaps derived
from naturally occurring fatty acids, for example, the fatty acids from beef tallow.
[0046] 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.
[0047] Specific nonionic surfactant compounds are alkyl (C
8-22) phenol-ethylene oxide condensates, the condensation products of linear or branched
aliphatic C
8-20 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.
[0048] Especially preferred are the primary and secondary alcohol ethoxylates, especially
the C
9-11 and C
12-15 primary and secondary alcohols ethoxylated with an average of from 5 to 20 moles
of ethylene oxide per mole of alcohol.
[0049] 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.
[0050] Many nonionic surfactants are liquids. These may be absorbed onto particles of the
composition.
[0051] In a machine dishwashing tablet the surfactant may be wholly nonionic, in an amount
below 5 wt% of the whole tablet although it is known to include some anionic surfactant
and to use up to 10 wt% surfactant in total.
Detergency Builder
[0052] A composition which is used in tablets of the invention will usually contain from
5 to 80%, more usually 15 to 60% by weight of detergency builder. This may be provided
wholly by water soluble materials (such as the phosphate builder with the hydration
content of more than 5.5 wt%), but may also in part be 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.
[0053] Alkali metal aluminosilicates are sometimes 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 Na
2O.Al
2O
3. 0.8 - 6 SiO
2. xH
2O
[0054] These materials contain some bound water (indicated as "xH2O") 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 SiO
2 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.
[0055] 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.
[0056] 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 "SKS-6"). NaSKS-6 has the delta-Na
2SiO
5 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
xO
2x+1·yH
2O 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.
[0057] 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. As described above the average moisture content of the phosphate
builder present in the compacted particulate phase(s) is at least 5.5 wt%, more preferred
more than 7.5 wt% most preferred more than 10 wt% up to 20 wt% or even total hydration
(22.7 wt%for STP hexa hydrate).
[0058] 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/maleic copolymers,
and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates,
oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates,
carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates.
[0059] At least one region (preferably the compacted 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
[0060] Tablets according to the invention may contain a bleach system in at least one region
of a tablet, preferably in the compacted particulate phase. This bleach system 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.
[0061] 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.
[0062] 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
[0063] The detergent tablets of the invention may also contain (preferably in the region
of the compacted particulate phase) 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, lipases, 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.
[0064] The detergent tablets of the invention may also contain (preferably in the region
of the compacted particulate phase) 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.
[0065] An antifoam material is advantageously included (preferably in the region of the
compacted particulate phase), 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.
[0066] 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.
[0067] 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 region of the compacted particulate phase of the tablet.
[0068] Further ingredients which can optionally be employed in a region of a fabric washing
detergent of the invention tablet (preferably the region of the compacted particulate
phase) 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.
[0069] Further ingredients which can optionally be used in tablets of the invention, preferably
in the second region are dispersing aids. Examples of suitable dispersing aids are
water-swellable polymers (e.g. SCMC) highly soluble materials (e.g. sodium citrate,
potassium carbonate or sodium acetate) or sodium tripolyphospate with preferably at
least 40% of the anhydrous phase I form.
Particle Size and Distribution
[0070] The second region of a detergent tablet of this invention, is a preferably a matrix
of compacted particles.
[0071] Preferably the particulate composition has an average particle size in the range
from 200 to 2000 µm, more preferably from 250 to 1400 µm. Fine particles, smaller
than 180 µm or 200 µm may be eliminated by sieving before tabletting, if desired,
although we have observed that this is not always essential.
[0072] While the starting particulate composition may in principle have any bulk density,
the present invention is especially relevant to tablets made by compacting powders
of relatively high bulk density, because of their greater tendency to exhibit disintegration
and dispersion problems. Such tablets have the advantage that, as compared with a
tablet derived from a low bulk density powder, a given dose of composition can be
presented as a smaller tablet.
[0073] Thus the starting particulate composition may suitably have a bulk density of at
least 400 g/litre, preferably at least 500 g/litre, and perhaps at least 600 g/litre.
[0074] 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.
[0075] 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.
[0076] The size of a tablet will suitably range from 10 to 160 grams, preferably from 15
to 60 g, depending on the conditions of intended use, and whether it represents a
dose for an average load in a fabric washing or dishwashing machine or a fractional
part of such a dose. The tablets may be of any shape. However, for ease of packaging
they are preferably blocks of substantially uniform cross-section, such as cylinders
or cuboids. The overall density of a tablet preferably lies in a range from 1040 or
1050gm/litre up to 1600gm/litre.
[0077] The invention will further be illustrated in the following examples:
Note: STP used in all examples was 70% in Phase I form
I.-Preparation of the Compacted Particulate Phase(s)
Example 1
[0078] Detergent tablets were manufactured by introducing 21 grammes of a particulate composition
into a tablet mould having an diameter of 45 mm. Composition A (comparative example)
comprised a STP phosphate builder with a hydration water content of 3.5 wt%. Composition
B comprised a mixture of STP having a hydration water content of 3.5 wt% (Polypray
H) and STP having a hydration water content of 13.4 wt%. The high moisture STP is
prepared by spraydrying Polypray H with water followed by drying to the moisture content
indicated.
[0079] Both mixtures were compressed until tablets of a tablets strength (Fmax) of about
95 N were obtained. Formulation A required the use of a compression pressure of about
32 kN to achieve the desired strength. Formulation B only required a compression pressure
of about 6 kN. The higher compression pressure for the comparative tablets leads to
a lower porosity and a lower rate of dissolution/dispersion for composition A as compared
to composition B according to the invention.
Ingredient |
Composition A; parts by weight |
Composition B; parts by weight |
STP (Polypray H; 3.5% moisture) |
60 |
27 |
STP (L2209; moisture 13.4 wt%) |
- |
33 |
Antifoam granule |
3.5 |
3.5 |
Fluorescer adjunct |
3 |
3 |
Sodium disilicate |
5 |
5 |
TAED (83%) |
5 |
5 |
Sodium percarbonate |
21 |
21 |
EDTMP |
2.5 |
2.5 |
Example 2:
[0080] Example I was repeated by replacing the 60 parts by weight of STP by:
Composition C: a 75/25 mixture of Polypray H (3.5% moisture) and fully hydrated STP
(22.7 % moisture)
Composition D: a 50/50 mixture of Polypray H (3.5% moisture) and fully hydrated STP
(22.7 % moisture)
Composition A (as in example I) required a compression force of about 61 kN in order
to obtain an Fmax of about 50 N. Composition C required a compression force of about
48 kN in order to obtain an Fmax of about 50N.
Compsition D required a compression force of about 40 kN to obtain an Fmax of about
50 N.
Example 3
[0081] Example I was repeated by replacing the 60 parts by weight of STP by:
Composition E: a 75/25 mixture of 75 parts Polypray H (3.5% moisture) and 25 parts
of fully hydrated STP (22.7 % moisture)comprising 6wt% on phosphate of sodium silicate.
Composition F: a 50/50 mixture of 75 parts Polypray H (3.5% moisture) and 25 parts
of fully hydrated STP (22.7 % moisture) comprising 6wt% on phosphate of sodium silicate.
Composition A (as in example I) required a compression force of about 72 kN in order
to obtain an Fmax of about 61 N. Composition E required a compression force of about
47 kN in order to obtain an Fmax of about 61 N.
Compsition F required a compression force of about 33 kN to obtain an Fmax of about
61 N.
II.- Preparation of smooth phase(s)
Example I
[0082] 7 kg of anionic surfactant (Dobanic acid 103 ex Shell) and 6kg of nonionic surfactant
(Lutensol AO7 ex BASF) were mixed and neutralised to a pH of 9 using a 50% NaOH solution.
[0083] 10 wt% (based on the weight of neutralised blend) of soap fatty acid (Pristerene
4916 fatty acid ex Uniqema) was added. 5 to 10 wt% (based on the weight of neutralised
blend) dipropylene glycol (ex Vopak) was also added to the mixture. The mixture was
further neutralised with a 50% NaOH solution to a pH of 11.
[0084] After neutralisation to pH of 11, the mixture was pumped into a sequence of 2 stainless
steel tubes by a Maag Sinox P7 pump or a piston pump, type SIBa HK 05016SST4000M000
ex Prominent, Vleuten (NL). Both tubes were double jacketed. The first tube was 2.5m
long and had an inner diameter of 73mm. The second tube was 1.5m long and had an inner
diameter of 45mm. The tubes were connected by a 10cm long pipe.
[0085] The extrusion was performed in the absence of a die-head.
[0086] The mixture was pumped into the tubes at a temperature of 85°C at a throughput of
4 kg/hr. The first tube was cooled using a water bath at 40°C. The second tube was
cooled using a 50:50 weight mixture of ethylene glycol and water. The coolant temperature
was -15°C. The material coming out of the second tube had a temperature of abour 20
C and was collected and divided into bars of around 0.5m.
[0087] After storage the bars were cut into slices of 5 gramme each.
III.- Preparation of Multiphase tablets
Example 1:
[0088] A detergent powder was made of the following composition by pregranulating the granule
ingredients, followed by post-dosing the rest of the ingredients
Ingredient |
Parts by weight |
Granules |
|
Na-las |
1.1 |
Nonionic 7EO |
0.5 |
C12 soap |
0.1 |
NaAc.3aq |
0.3 |
Zeolite A24 |
2.4 |
Light soda ash |
0.4 |
Moisture/minors |
0.4 |
Post-dose |
|
EAG (17% silicone) |
3.0 |
Fluorescer (15%) |
2.2 |
STP * |
60.0 |
Na-disilicate (80%) |
3.8 |
TAED (83%) |
4.3 |
Percarbonate |
16.9 |
Dequest 2047 |
1.9 |
Minors/ enzymes/colour |
to 100 |
Note: STP as in composition B described above. |
[0089] Smooth parts of 5 gramme were prepared as above.
The tablets were made as follows: 20 grammes of the powder are inserted into a 45
mm die of a tabletting machine, optionally followed by a flattening step, followed
by addition of a single smooth part on top of the powder bed. After addition of the
smooth onto the powder bed or flattened powder, the whole material is compressed at
30kN into a single tablet, followed by ejection of the tablet. This results in a tablet
with a smooth part embedded in the cleaning tablet. The density of the powdered region
is 1.5 kg/litre, the density of the smooth part is 1.0 kg/litre. The height of the
smooth part after compression is 3.4 mm, of the powdered part 11 mm.