[0001] The present invention relates to a process for the continuous preparation of a granular
detergent composition or component having a high bulk density and good flow properties.
In such compositions and components it is known to use crystalline Zeolite A which
is a water-insoluble, crystalline material well-known in the detergent art as a builder
which is particularly suited to removing cations such as calcium and magnesium from
hard water.
[0002] Crystalline Zeolite A is a very finely divided powder. It has been common practice
to process the finely divided powder into the form of larger granules (typically 400
to 1000 micrometers) before incorporation into finished products, especially finished
detergent compositions. Various granulation processes are known including spray drying
and agglomeration. Conventional agglomeration processes in which Zeolite A is used
as one of the components have long been known in the prior art :
GB2005715, published on 25th April 1979 describes an agglomeration process based upon
Zeolite A. The Zeolite A is agglomerated along with carbonate/bicarbonate to make
nonionic surfactant agglomerates.
US-A-5 468 516 describes a process for producing nonionic detergent granules which
have a high bulk density, excellent powder fluidity and non-caking property, wherein
(inter alia) 20 to 95 parts by weight of a builder, 1 to 20 parts by weight of a porous
oil absorbent carrier and from 10 to 60 parts by weight of a nonionic surfactant are
processed.
WO93/25378, published on 23rd December 1993, discloses a process for making granular
detergents comprising Zeolite A. The Zeolite A is agglomerated with a high active,
neutralised surfactant paste in a high speed mixer and a moderate speed mixer/agglomerator
to make anionic surfactant agglomerates.
[0003] One of the factors which limits the surfactant activity of the prior art mentioned
above is the capacity of Zeolite A to absorb liquid organic materials. It has been
suggested that replacing Zeolite A by Zeolite P (specifically Zeolite MAP) could address
this problem :
EP521635, published on 7th January 1993, discloses granular detergents made using
from 10% to 100% of Zeolite MAP. Zeolite MAP has a different chemical composition
to Zeolite A. In Example 1 of this patent application it is reported that the oil
absorbing capacity of Zeolite MAP is 41.6 ml/100g, and that this is higher than measured
samples of Zeolite A for which it is 26 to 35.5 ml/100g.
However modifying the chemical structure of conventional crystalline Zeolite A (i.e.
modifying the stoichiometric ratios of Si, Al, Na, O, H) is not always desirable because
other properties and characteristics cf the Zeolite are necessarily affected.
[0004] The object of the invention is to provide a granulation process for making granular
detergents which incorporates highly absorbent crystalline Zeolite into granular agglomerates,
without losing any of the builder capabilities, especially calcium exchange capacity
and calcium exchange rate.
[0005] According to the invention this object is achieved by using a modified crystalline
Zeolite A having higher oil absorption capacities in a process as specified in claim
1. The Zeolite A has modified physical characteristics (i.e. crystallinity, surface
area characteristics, moisture level etc.) rather than a modified chemical structure
in order to achieve an oil absorbing capacity of at least 40 ml/100g. In this way
the excellent builder properties of Zeolite A may still be utilised.
[0006] It is a further object of the present invention to provide a granulation process
for making granular detergents having improved processability, and amount of oversize
particles (or "lumps") being formed in the process being reduced.
Summary of the Invention
[0007] The objects of the invention are achieved by a process for the preparation of a granular
detergent composition or component having a bulk density greater than 650 g/l, from
20% to 70% by weight of crystalline zeolite A having an oil absorbing capacity of
at least 40ml/100g, at least 30% by weight of anionic surfactant, the ratio of the
crystalline zeolite A to the anionic surfactant being less than 1:1, which comprises
the step of dispersing a liquid binder, which is a paste comprising at least 10% by
weight of a neutralised anionic surfactant and having a viscosity of at least 10000mPas,
throughout a powder stream in a high speed mixer to form granular agglomerates, wherein
the powder stream comprises crystalline zeolite A having an oil absorbing capacity
of at least 40 ml/100g, preferably at least 45 ml/100g and most preferably at least
50 ml/100g.
[0008] In a preferred embodiment of the invention the granular agglomerates are formed by
mixing in the high speed mixer for a residence time of from 2 seconds to 30 seconds,
followed by the step of
further mixing in a moderate speed mixer/agglomerator for a residence time through
the moderate speed mixer of less than 5 minutes, preferably less than 2 minutes, in
which, optionally, a finely divided powder may be added.
Detailed Description of the Invention
[0009] Granulation in the context of the present invention is defined as a process of making
a granulated product which is an agglomerate of particles that itself behaves as a
particle (according to S.A. Kuti, "Agglomeration - The Practical Alternative", published
in Journal American Oil Chemists' Society, Volume 55, January 1978). The granular
agglomerate is defined herein as the product of such a granulation process. Kuti goes
on to state that "the agglomerate is usually formed by blending solids with liquids
that serve as adhesive agents. But a lump-free liquid-solids blend is often a difficult
task to produce."
[0010] In the present invention the "solids" referred to by Kuti will comprise crystalline
Zeolite A having certain physical characteristics to be defined in more detail below.
It has now been found that this choice of "solids" contributes greatly to fulfilling
the task of producing a lump-free liquid-solids blend.
[0011] The essential component of the granular agglomerate of the present invention is crystalline
Zeolite A of the formula
(Na2O) . (Al2O3) . x (SiO2) . wH2O
wherein x is from 1 to 2, and w is from 0 to 6.
[0012] Hydrated, or partially hydrated sodium Zeolite A with a particle size of up to 10
microns is preferred.
[0013] In an especially preferred embodiment, x=2, the Zeolite A material has the formula
Na
12 [(AlO
2)
12 (SiO2)
12] · (6w') H
2O
wherein (6w') is from about 20 to about 30, especially about 27, and has a particle
size generally less than about 5 microns.
[0014] The Zeolite A materials herein may contain up to about 28% water. Preferred builder
materials are in hydrated form and contain from about 5% to about 28% of water by
weight. Highly preferred crystalline aluminosilicate ion exchange materials contain
from about 10% to about 22% water in their crystal matrix. The crystalline Zeolite
A materials are further characterized by a particle size diameter of from about 0.1
micron to about 10 microns. Preferred ion exchange materials have a particle size
diameter of from about 0.2 micron to about 4 microns. The term "particle size diameter"
herein represents the average particle size diameter by weight of a given ion exchange
material as determined by conventional analytical techniques such as, for example,
microscopic determination utilizing a scanning electron microscope. The crystalline
Zeolite A materials herein are usually further characterized by their calcium ion
exchange capacity, which is at least about 200 mg equivalent of CaCO
3 water hardness/g of aluminosilicate, calculated on an anhydrous basis, and which
generally is in the range of from about 300 mg eq./g to about 352 mg eq./g. The Zeolite
A materials herein are still further
characterized by their calcium ion exchange rate which is at least about 2 grains
Ca
++/gallon/minute/gram/gallon (0.13g Ca
++/litre/minute/gram/litre) of aluminosilicate (anhydrous basis), and generally lies
within the range of from about 2 grains/gallon/minute/gram/gallon(0.13g Ca
++/litre/minute/gram/litre) to about 6 grains/gallon/minute/gram/gallon (0.39g Ca
++/litre/minute/gram/litre), based on calcium ion hardness. Optimum aluminosilicate
for builder purposes exhibit a calcium ion exchange rate of at least about 4 grains/gallon/minute/gram/gallon
(0.26g Ca
++/litre/minute/gram/litre).
[0015] Zeolite A materials useful in the practice of this invention are commercially available.
The aluminosilicates useful in this invention are crystalline in structure and can
be naturally occurring aluminosilicates or synthetically derived. A method for producing
aluminosilicate ion exchange materials is discussed in U.S. Pat. No. 3,985,669, Krummel
et al., issued Oct. 12, 1976, incorporated herein by reference.
[0016] It is an essential feature of the present invention that the Zeolite A used in the
formation of the granular agglomerates has an oil absorption capacity of at least
40 ml/100g, preferably at least 45 ml/100g and most preferably at least 50 ml/100g.
The method for determining the oil absorption capacity is defined below under the
heading "Test Methods".
[0017] Optionally other forms of zeolite may be present in combination with the zeolite
A, such as zeolite P, zeolite X, and zeolite HS.
[0018] The granular agglomerates of the present invention also comprise other detergent
ingredients.
[0019] Water-soluble salts of the higher fatty acids, i.e., "soaps", are useful anionic
surfactants in the compositions herein. This includes alkali metal soaps such as the
sodium, potassium, ammonium, and alkylammonium salts of higher fatty acids containing
from about 8 to about 24 carbon atoms, and preferably from about 12 to about 18 carbon
atoms. Soaps can be made by direct saponification of fats and oils or by the neutralization
of free fatty acids. Particularly useful are the sodium and potassium salts of the
mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium
tallow and coconut soap.
[0020] Useful anionic surfactants also include the water-soluble salts, preferably the alkali
metal, ammonium and alkylolammonium salts, of organic sulfuric reaction products having
in their molecular structure an alkyl group containing from about 10 to about 20 carbon
atoms and a sulfonic acid or sulfuric acid ester group. (Included in the term "alkyl"
is the alkyl portion of acyl groups.) Examples of this group of synthetic surfactants
are the sodium and potassium alkyl sulfates, especially those obtained by sulfating
the higher alcohols (C
8-C
18 carbon atoms) such as those produced by reducing the glycerides of tallow or coconut
oil; and the sodium and potassium alkyl benzene sulfonates in which the alkyl group
contains from about 9 to about 15 carbon atoms, in straight or branched chain configuration,
e.g., those of the type described in U.S. Pat. Nos. 2,220,099 and 2,477,383; and methyl
ester sulphonates. Especially valuable are linear straight chain alkyl benzene sulfonates
in which the average number of carbon atoms in the alkyl group is from about 11 to
13, abbreviated as C
11-C
13 LAS.
[0021] Other anionic surfactants herein are the sodium alkyl glyceryl ether sulfonates,
especially those ethers of higher alcohols derived from tallow and coconut oil; sodium
coconut oil fatty acid monoglyceride sulfonates and sulfates; sodium or potassium
salts of alkyl phenol ethylene oxide ether sulfates containing from about 1 to about
10 units of ethylene oxide per molecule and wherein the alkyl groups contain from
about 8 to about 12 carbon atoms; and sodium or potassium salts of alkyl ethylene
oxide ether sulfates containing from about 1 to about 10 units of ethylene oxide per
molecule and wherein the alkyl group contains from about 10 to about 20 carbon atoms.
[0022] Other useful anionic surfactants herein include the water-soluble salts of esters
of alpha-sulfonated fatty acids containing from about 6 to 20 carbon atoms in the
fatty acid group and from about 1 to 10 carbon atoms in the ester group; water-soluble
salts of 2-acyloxy-alkane-1-sulfonic acids containing from about 2 to 9 carbon atoms
in the acyl group and from about 9 to about 23 carbon atoms in the alkane moiety;
alkyl ether sulfates containing from about 10 to 20 carbon atoms in the alkyl group
and from about 1 to 30 moles of ethylene oxide; watersoluble salts of olefin sulfonates
containing from about 12 to 24 carbon atoms; and beta-alkyloxy alkane sulfonates containing
from about 1 to 3 carbon atoms in the alkyl group and from about 8 to about 20 carbon
atoms in the alkane moiety. Although the acid salts are typically discussed and used,
the acid neutralization cam be performed as part of the fine dispersion mixing step.
[0023] Water-soluble nonionic surfactants are also useful as surfactants in the compositions
of the invention. Indeed, preferred processes use anionic/nonionic blends. Such nonionic
materials include compounds produced by the condensation of alkylene oxide groups
(hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic
or alkyl aromatic in nature. The length of the polyoxyalkylene group which is condensed
with any particular hydrophobic group can be readily adjusted to yield a water-soluble
compound having the desired degree of balance between hydrophilic and hydrophobic
elements.
[0024] Suitable nonionic surfactants include the polyethylene oxide condensates of alkyl
phenols, e.g., the condensation products of alkyl phenols having an alkyl group containing
from about 6 to 16 carbon atoms, in either a straight chain or branched chain configuration,
with from about 4 to 25 moles of ethylene oxide per mole of alkyl phenol.
[0025] Preferred nonionics are the water-soluble condensation products of aliphatic alcohols
containing from 8 to 22 carbon atoms, in either straight chain or branched configuration,
with from 1 to 25 moles of ethylene oxide per mole of alcohol, especially 2 to 7 moles
of ethylene oxide per mole of alcohol. Particularly preferred are the condensation
products of alcohols having an alkyl group containing from about 9 to 15 carbon atoms;
and condensation products of propylene glycol with ethylene oxide.
[0026] Other preferred nonionics are polyhydroxy fatty acid amides which may be prepared
by reacting a fatty acid ester and an N-alkyl polyhydroxy amine. The preferred amine
for use in the present invention is N-(R1)-CH2(CH2OH)4-CH2-OH and the preferred ester
is a C12-C20 fatty acid methyl ester. Most preferred is the reaction product of N-methyl
glucamine (which may be derived from glucose) with C12-C20 fatty acid methyl ester.
[0027] Methods of manufacturing polyhydroxy fatty acid amides have been described in WO
9206073, published on 16th April, 1992. This application describes the preparation
of polyhydroxy fatty acid amides in the presence of solvents. In a highly preferred
embodiment of the invention N-methyl glucamine is reacted with a C12-C20 methyl ester.
It also says that the formulator of granular detergent compositions may find it convenient
to run the amidation reaction in the presence of solvents which comprise alkoxylated,
especially ethoxylated (EO 3-8) C12-C14 alcohols (page 15, lines 22-27). This directly
yields nonionic surfactant systems which are suitable for use in the present invention,
such as those comprising N-methyl glucamide and C12-C14 alcohols with an average of
3 ethoxylate groups per molecule.
[0028] Semi-polar nonionic surfactants include water-soluble amine oxides containing one
alkyl moiety of from about 10 to 18 carbon atoms and 2 moieties selected from the
group consisting of alkyl groups and hydroxyalkyl groups containing from 1 to about
3 carbon atoms; water-soluble phosphine oxides containing one alkyl moiety of about
10 to 18 carbon atoms and 2 moieties selected from the group consisting of alkyl groups
and hydroxyalkyl groups containing from about 1 to 3 carbon atoms; and water-soluble
sulfoxides containing one alkyl moiety of from about 10 to 18 carbon atoms and a moiety
selected from the group consisting of alkyl and hydroxyalkyl moieties of from about
1 to 3 carbon atoms.
[0029] Ampholytic surfactants include derivatives of aliphatic or aliphatic derivatives
of heterocyclic secondary and tertiary amines in which the aliphatic moiety can be
either straight or branched chain and wherein one of the aliphatic substituents contains
from about 8 to 18 carbon atoms and at least one aliphatic substituent contains an
anionic water-solubilizing group.
[0030] Zwitterionic surfactants include derivatives of aliphatic quaternary ammonium phosphonium,
and sulfonium compounds in which one of the aliphatic substituents contains from about
8 to 18 carbon atoms.
[0031] Useful cationic surfactants include water-soluble quaternary ammonium compounds of
the form R
4R
5R
6R
7N
+X
-, wherein R
4 is alkyl having from 10 to 20, preferably from 12-18 carbon atoms, and R
5, R
6 and R
7 are each C
1 to C
7 alkyl preferably methyl; X
- is an anion, e.g. chloride. Examples of such trimethyl ammonium compounds include
C
12-14 alkyl trimethyl ammonium chloride and cocalkyl trimethyl ammonium methosulfate.
[0032] The granular detergents of the present invention can contain neutral or alkaline
salts which have a pH in solution of seven or greater, and can be either organic or
inorganic in nature. The builder salt assists in providing the desired density and
bulk to the detergent granules herein. While some of the salts are inert, many of
them also function as detergency builder materials in the laundering solution.
[0033] Examples of neutral water-soluble salts include the alkali metal, ammonium or substituted
ammonium chlorides, fluorides and sulfates. The alkali metal, and especially sodium,
salts of the above are preferred. Sodium sulfate is typically used in detergent granules
and is a particularly preferred salt. Citric acid and, in general, any other organic
or inorganic acid may be incorporated into the granular detergents of the present
invention as long as it is chemically compatible with the rest of the agglomerate
composition.
[0034] Other useful water-soluble salts include the compounds commonly known as detergent
builder materials. Builders are generally selected from the various water-soluble,
alkali metal, ammonium or substituted ammonium phosphates, polyphosphates, phosphonates,
polyphosphonates, carbonates, silicates, borates, and polyhyroxysulfonates. Preferred
are the alkali metal, especially sodium, salts of the above.
[0035] Specific examples of inorganic phosphate builders are sodium and potassium tripolyphosphate,
pyrophosphate, polymeric metaphosphate having a degree of polymerization of from about
6 to 21, and orthophosphate. Examples of polyphosphonate builders are the sodium and
potassium salts of ethylene diphosphonic acid, the sodium and potassium salts of ethane
1-hydroxy-1,1-diphosphonic acid and the sodium and potassium salts of ethane, 1,1,2-triphosphonic
acid. Other phosphorus builder compounds are disclosed in U.S. Pat. Nos. 3,159,581;
3,213,030; 3,422,021; 3, 422, 137; 3,400,176 and 3,400,148, incorporated herein by
reference.
[0036] Examples of nonphosphorus, inorganic builders are sodium and potassium carbonate,
bicarbonate, sesquicarbonate, tetraborate decahydrate, and silicate having a molar
ratio of SiO
2 to alkali metal oxide of from about 0.5 to about 4.0, preferably from about 1.0 to
about 2.4. The compositions made by the process of the present invention does not
require excess carbonate for processing, and preferably does not contain over 2% finely
divided calcium carbonate as disclosed in U.S. Pat. No. 4,196,093, Clarke et al.,
issued Apr.1, 1980, and is preferably free of the latter.
Polymers
[0037] Also useful are various organic polymers, some of which also may function as builders
to improve detergency. Included among such polymers may be mentioned sodium carboxy-lower
alkyl celluloses, sodium lower alkyl celluloses and sodium hydroxy-lower alkyl celluloses,
such as sodium carboxymethyl cellulose, sodium methyl cellulose and sodium hydroxypropyl
cellulose, polyvinyl alcohols (which often also include some polyvinyl acetate), polyacrylamides,
polyacrylates and various copolymers, such as those of maleic and acrylic acids. Molecular
weights for such polymers vary widely but most are within the range of 2,000 to 100,000.
Other suitable polymers are polyamine N-oxide polymers, copolymers of N-vinylpyrrolidone
and N-vinylimidazole, polyvinylpyrrolidone polymers, polyvinyloxazolidones and polyvinylimidazoles
or mixtures thereof.
[0038] Polymeric polycarboxyate builders are set forth in U.S. Patent 3,308,067, Diehl,
issued March 7, 1967. Such materials include the water-soluble salts of homo-and copolymers
of aliphatic carboxylic acids such as maleic acid, itaconic acid, mesaconic acid,
fumaric acid, aconitic acid, citraconic acid and methylenemalonic acid.
Silicone Oils
[0039] Particulate suds suppressors may also be incorporated either directly in the agglomerates
herein by way of the powder stream into the agglomerating unit, or in the finished
composition by dry adding. Preferably the suds suppressing activity of these particles
is based on fatty acids or silicones.
In one embodiment of the present invention the silicone oil is adsorbed onto the specified
Zeolite A.
Optionals
[0040] Other ingredients commonly used in detergent compositions can be included in the
compositions of the present invention. These include flow aids, color speckles, bleaching
agents and bleach activators, suds boosters or suds suppressors, antitarnish and anticorrosion
agents, soil suspending agents, soil release agents, dyes, fillers, optical brighteners,
germicides, pH adjusting agents, nonbuilder alkalinity sources, hydrotropes, enzymes,
enzyme-stabilizing agents, chelating agents and perfumes.
[0041] These optional ingredients, especially optical brighteners, may be incorporated either
directly in the agglomerates herein or may be components of separate particles suitable
for dry adding to the agglomerates of the present invention.
Processing
[0042] Useful agglomeration processes are defined in EP-A-510746, published on 28th October
1992, and in WO93/25378, published on 23rd December 1993. These applications describe
the agglomeration of solids with a high active neutralised surfactant paste. However
it will be appreciated that the high active neutralised paste could be replaced fully
or in part by other surfactants, especially nonionic surfactants (as in EP643130,
published on 15th March 1995), or by organic polymers or silicone oils. Preferred
embodiments of the process are described in more detail in the Examples below.
TEST METHOD
[0043] Oil absorption values can be determined by following British Standards, BS3483 :
Part 7 :1982 (corresponding to ISO 787/5-1980). A 5 gram sample of Zeolite A having
a free alkalinity of less than 0.5% should be used. Oil absorption value (OAV) is
expressed as :

EXAMPLES
[0044] All values are expressed in % by weight. Zeolite levels are expressed on a hydrated
basis (including 15% by weight of bound water)
| |
Ex. 1 |
Comp. Ex. A |
| Zeolite A * |
32 |
- |
| Zeolite A # |
- |
32 |
| C12-15 AS |
24 |
24 |
| C12-15 AE3S |
6 |
6 |
| Sodium |
25 |
25 |
| Carbonate |
|
|
| Co-polymer |
- |
- |
| Nonionic Surfactant |
- |
- |
| Water |
5 |
5 |
| Misc. |
8 |
8 |
Zeolite A* has an oil absorption capacity of 45.5 ml/100g supplied by Industrial Zeolites
(UK) Ltd. of Thurrock, Essex, England.
Zeolite A # has an oil absorption capacity of 36 ml/100g supplied by Degussa under
the Trade Name Wessalith®.
C12-15AS is sodium alkyl sulphate, the alkyl chains principally comprising C12 to
C15.
C12-15AE3S is sodium alkyl ether sulphate, the alkyl chains principally comprising
C12 to C15, and with an average of 3 ethoxy groups per molecule.
Co-polymer is a co-polymer of acrylic and maleic acid. Nonionic surfactant comprises
7 parts of ethoxylated alcohol, the alkyl chains principally comprising C12 to C15,
and with an average of 3 ethoxy groups per molecule; and 3 parts of C12-14 polyhydroxy
fatty acid amide.
Misc is mainly sulphate with some other minor impurities. |
[0045] Granular agglomerates having the composition of Example 1 were prepared by the following
process. The powdered raw materials (Zeolite A and sodium carbonate) were added to
the pan of an Eirich® mixer rotated at 64 rpm and mixed for 10 seconds. The mixer
pan was then stopped and preheated surfactant paste (50°C), 80% surfactant active
in aqueous solution, was then added in slices into a hollow formed in the middle of
the powder. Loose powder being scooped over the paste to completely cover it. The
mixer was then started again with pan rotating at 64 rpm, and choppers set at 2500
rpm. The mixing was stopped when granular agglomerates started to form (at this point
the current drawn by the Eirich rose from 2.8 to 3 amps.
[0046] The resulting granular agglomerates were free-flowing and had less than 25% by weight
of oversized particles (oversized particles be considered as those having particle
size of greater than 1600 micrometers).
[0047] Granular agglomerates having the composition of Comparative Example A were prepared
by the same process as Example 1, using the same time of mixing the powders and paste
as that used in Example 1. The resulting granular agglomerates had greater than 25%
by weight of oversized particles (oversized particles be considered as those having
particle size of greater than 1600 micrometers).