[0001] The present invention relates to a process for making granular detergent which have
a high surfactant activity and which are free-flowing and rapidly dissolving. In another
aspect the invention relates to a premixed free-flowing powder which comprises hydrophobic
silica and a hygroscopic powder which comprises a polymer. In a third aspect the invention
relates to high active, high bulk density granular detergent compositions.
[0002] Granular detergent granules comprising low levels of certain polymers which provide
structure or strength to the granule are known and have been made by spray drying
aqueous solutions or slurries comprising the polymer. However, spray dried granules
have low bulk densities (for example 350-550 g/l). Further treatment is necessary
in order to increase the bulk density and various methods have been proposed to do
this. One approach is to apply mechanical work to the spray dried powder in order
to reduce its porosity and increase its bulk density. Another approach is to granulate
a liquid or paste, typically in the presence of a powder. Polymers may be added to
such a process either as a component of the liquid/paste, or as a component of the
powder. Examples in the prior art of the such processes include:
[0003] EPA 421 664, published on 10th April, 1992, describes high bulk density compositions
comprising polymer and water soluble inorganic component. Compositions comprising
surfactants and hydrophobic silica are not foreseen.
[0004] EPA 510 746, published on 28th October, 1992, describes a process of fine dispersion
mixing of a viscous surfactant paste with detergent powders to form a granular detergent.
Polymers and silica are mentioned as useful ingredients in such a detergent composition.
However there is no suggestion of how they may be most usefully combined.
[0005] EPA 513 824, published on 19th November, 1992 describes a process for making granular
detergents which comprise up to 60% by weight of nonionic surfactant. It suggests
that various powder components may be premixed in order to improve physical properties,
but it does not indicate which powders may be advantageously premixed.
[0006] When it is required to use higher levels of polymers in high bulk density granular
detergent components, the hygroscopic nature of many polymers presents a problem.
In particular this is the case when the component also comprises a high level of surfactant.
Hygroscopic powders which are bound into the surface of the detergent component cause
the component to readily absorb water which encourages gel formation, caking of the
detergent powder and poor dispensing and dissolution properties.
[0007] The present invention aims to solve this problem by providing a process in which
the surface of hygroscopic powders which comprise polymers is modified before the
high bulk density detergent granules are formed. This surface modification effect
is provided by premixing the hygroscopic powder with hydrophobic silica.
[0008] The present invention further aims to provide a high bulk density detergent composition
which comprises high levels of detergent surfactant and polymers.
Summary of the Invention
[0009] A process for making a high active granular detergent component or composition having
a bulk density of at least 650 g/l which comprises the steps of:
i) making a paste or liquid which comprises at least 40% by weight of a surfactant
selected from anionic and nonionic surfactants,
ii) mixing said surfactant paste or liquid with a powder to form a mixture which may
be in the form of either a paste or a cohesive powder;
iii) forming granules by fine dispersion mixing or granulation of said mixture, optionally
in the presence of an effective amount of one or more additional powders; wherein
the powder used in step ii) comprises a free-flowing, premixed powder comprising from
0.5% to 10% by weight of a hydrophobic silica and from 75% to 99.5% by weight of a
hygroscopic powder comprising a polymer.
Detailed Description of the Invention
[0010] The first aspect of the present invention relates to a process for making a high
active granular detergent component or composition having a bulk density of at least
650 g/l. The process comprises the steps of:
i) making a paste or liquid which comprises at least 40% by weight of a surfactant
selected from anionic and nonionic surfactants,
ii) mixing said surfactant paste or liquid with a powder wherein the powder is a free-flowing,
premixed powder comprising from 0.5% to 10% by weight of a hydrophobic silica and
from 75% to 99.5% by weight of a hygroscopic powder comprising a polymer. The resulting
mixture may be in the form of either a paste or a cohesive powder; and
iii) forming granules by fine dispersion mixing or granulation of said mixture, optionally
in the presence of an effective amount of one or more additional powders.
[0011] Preferably the polymer component of the hygroscopic powder is chosen from the group
consisting of polymers or co-polymers of acrylic and maleic acid, polyvinyl pyrrolidone,
polyvinyl pyrridine N oxide, carboxymethyl cellulose, polyaspartate, and starch. Preferably
the hydrophobic silica is used as a coating agent to coat, or partially coat the outer
surfaces of the hygroscopic powder.
[0012] One method of preparing the hygroscopic powder which is useful in the present invention
is to use a spray drying technique, wherein a two fluid nozzle is used in the spray
drying step. Most preferably compressed air is used as one of the fluids in the two
fluid nozzle.
[0013] In a preferred embodiment of the process the premixed hydrophobic silica and hygroscopic
polymer is mixed with the surfactant paste prior to the fine dispersion mixing of
step iii). One way of doing this is to use an extruder, for example a twin screw extruder.
[0014] An example of a range of typical compositions of the premixed hydrophobic silica
and hygroscopic polymer is:
a) from 80% to 95% by weight of a polymer;
b) from 1% to 5% by weight of hydrophobic silica;
c) up to 20% by weight of zeolite
In a further aspect the present invention relates to a granular detergent component
having a bulk density of at least 650 g/l and comprising:
a) at least 35% (preferably at least 45%, more preferably at least 55%) by weight
of surfactant;
b) from 5% to 25% (preferably from 8% to 15%) by weight polymer;
c) from 0.05% to 2.5% (preferably from 0.5% to 1%) by weight of hydrophobic silica;
The details of the process will now be described in more detail.
[0015] Firstly a high active surfactant paste is prepared. One or various aqueous pastes
of the salts of anionic surfactants is preferred for use in the present invention,
preferably the sodium salt of the anionic surfactant. In a preferred embodiment, the
anionic surfactant is preferably as concentrated as possible, (that is, with the lowest
possible moisture content possible that allows it to flow in the manner of a liquid)
so that it can be pumped at temperatures at which it remains stable. While granulation
using various pure or mixed surfactants is known, for the present invention to be
of practical use in industry and to result in particles of adequate physical properties
to be incorporated into granular detergents, an anionic surfactant should preferably
be a part of the paste in a concentration of above 10% by weight, preferably from
10-95%, more preferably from 20-95%, and most preferably from 40%-95% by weight.
[0016] It is preferred that the moisture in the surfactant aqueous paste is as low as possible,
while maintaining paste fluidity, since low moisture leads to a higher concentration
of the surfactant in the finished particle. Preferably the paste contains between
5 and 40% water, more preferably between 5 and 30% water and most preferably between
5 and 20% water. A highly attractive mode of operation for lowering the moisture of
the paste prior to entering the agglomerator without problems with very high viscosities
is the installation, in line, of an atmospheric or a vacuum flash drier whose outlet
is connected to the agglomerator.
[0017] It is preferable to use high active surfactant pastes to minimize the total water
level in the system during mixing, granulating and drying. Lower water levels allow
for: (1) a higher active surfactant to builder ratio, e.g., 1:1; (2) higher levels
of other liquids in the formula without causing dough or granular stickiness; (3)
less cooling, due to higher allowable granulation temperatures; and (4) less granular
drying to meet final moisture limits.
[0018] Two important parameters of the surfactant pastes which can affect the mixing and
granulation step are the paste temperature and viscosity. Viscosity is a function,
among others, of concentration and temperature, with a range in this application from
about 5,000 cps to 10,000,000 cps. Preferably, the viscosity of the paste entering
the system is from about 20,000 to about 100,000 cps. and more preferably from about
30,000 to about 70,000 cps. The viscosity of the paste of this invention is measured
at a temperature of 70°C and at a shear rate of from 10 to 50 sec⁻¹, in particular,
about 25 sec⁻¹.
The paste can be introduced into the mixer at an initial temperature between its
softening point (generally in the range of 40-60°C) and its degradation point (depending
on the chemical nature of the paste, e.g. alkyl sulphate pastes tend to degrade above
75-85°C). High temperatures reduce viscosity simplifying the pumping of the paste
but result in lower active agglomerates. The use of in-line moisture reduction steps
(e.g. flash drying), however, require the use of higher temperatures (above 100°C).
In the present invention, the activity of the agglomerates is maintained high due
to the elimination of moisture.
[0019] The introduction of the paste into the mixer can be done in many ways, from simply
pouring to high pressure pumping through small holes at the end of the pipe, before
the entrance to the mixer. While all these ways are viable to manufacture agglomerates
with good physical properties, it has been found that in a preferred embodiment of
the present invention the extrusion of the paste results in a better distribution
in the mixer which improves the yield of particles with the desired size. Most preferably
a twin screw extruder is used. The use of high pumping pressures prior to the entrance
in the mixer results in an increased activity in the final agglomerates. By combining
both effects, and introducing the paste through holes (extrusion) small enough to
allow the desired flow rate but that keep the pumping pressure to a maximum feasible
in the system, highly advantageous results are achieved.
High Active Surfactant Paste
[0020] The activity of the aqueous surfactant paste is at least 30% and can go up to about
95%; preferred activities are : 60-90% and 70-80%. The balance of the paste is primarily
water. At the higher active concentrations, little or no builder is required for cold
granulation of the paste. The resultant concentrated surfactant granules can be added
to dry builders or powders or used in conventional agglomeration operations. The aqueous
surfactant paste contains an organic surfactant selected from the group consisting
of anionic, nonionic, zwitterionic, ampholytic and cationic surfactants, and mixtures
thereof. Anionic surfactants are preferred. Surfactants useful herein are listed in
U.S. Pat. No. 3,664,961, Norris, issued May 23, 1972, and in U.S. Pat. No. 3,919,678,
Laughlin et al., issued Dec. 30, 1975. Useful cationic surfactants also include those
described in U.S. Pat. No. 4,222,905, Cockrell, issued Sept. 16, 1980, and in U.S.
Pat. 4,239,659, Murphy, issued Dec. 16, 1980. However, cationic surfactants are generally
less compatible with the aluminosilicate materials herein, and thus are preferably
used at low levels, if at all, in the present compositions. The following are representative
examples of surfactants useful in the present compositions.
[0021] 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.
[0022] 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 in a linear or branched chain 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 or natural surfactants are the sodium and potassium alkyl sulfates,
especially those obtained by sulfating the higher alcohols (C₈-C₁₈ 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. 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 C₁₁-C₁₃ LAS.
[0023] 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.
[0024] 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.
[0025] The preferred anionic surfactant pastes are mixtures of linear or branched alkylbenzene
sulfonates having an alkyl of 10-16 carbon atoms and alkyl sulfates having an alkyl
of 10-18 carbon atoms. These pastes are usually produced by reacting a liquid organic
material with sulfur trioxide to produce a sulfonic or sulfuric acid and then neutralizing
the acid to produce a salt of that acid. The salt is the surfactant paste discussed
throughout this document. The sodium salt is preferred due to end performance benefits
and cost of NaOH vs. other neutralizing agents, but is not required as other agents
such as KOH may be used.
[0026] Water-soluble nonionic surfactants are also useful as surfactants in the compositions
of the invention. Indeed, preferred processes use anionic/nonionic blends. A particularly
preferred paste comprises a blend of nonionic and anionic surfactants having a ratio
of from about 0.01:1 to about 1:1, more preferably about 0.05:1. Nonionics can be
used up to an equal amount of the primary organic surfactant. 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.
[0027] 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.
[0028] 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 4 to 25 moles of ethylene oxide per more of alcohol. Particularly preferred
are the condensation products of alcohols having an alkyl group containing from about
9 to 15 carbon atoms with from about 4 to 25 moles of ethylene oxide per mole of alcohol;
and condensation products of propylene glycol with ethylene oxide.
Other preferred nonionics are polyhydroxy fatty acid amides which may be produced
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 with C12-C20 fatty acid methyl ester.
Methods of manufacturing polyhydroxy fatty acid amides have been described in WO 92
6073, 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). Another class
of nonionic surfactants comprises alkyl polyglucoside compounds of general formula
RO (C
nH
2nO)
tZ
x
wherein Z is a moiety derived from glucose; R is a saturated hydrophobic alkyl group
that contains from 12 to 18 carbon atoms; t is from 0 to 10 and n is 2 or 3; x is
from 1.3 to 4, the compounds including less than 10% unreacted fatty alcohol and less
than 50% short chain alkyl polyglucosides. Compounds of this type and their use in
detergent compositions are disclosed in EP-B 0070074, 0070077, 0075996 and 0094118.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] Particularly preferred surfactants herein include linear alkylbenzene sulfonates
containing from about 11 to 14 carbon atoms in the alkyl group; alkyl sulfates containing
from about 12 to 18 carbon atoms in the alkyl group; coconutalkyl glyceryl ether sulfonates;
alkyl ether sulfates wherein the alkyl moiety contains from about 14 to 18 carbon
atoms and wherein the average degree of ethoxylation is from about 1 to 4; olefin
or paraffin sulfonates containing from about 14 to 16 carbon atoms; alkyldimethylamine
oxides wherein the alkyl group contains from about 11 to 16 carbon atoms; alkyldimethylammonio
propane sulfonates and alkyldimethylammonio hydroxy propane sulfonates wherein the
alkyl group contains from about 14 to 18 carbon atoms; soaps of higher fatty acids
containing from about 12 to 18 carbon atoms; condensation products of C9-C15 alcohols
with from about 3 to 8 moles of ethylene oxide, and mixtures thereof.
[0033] Useful cationic surfactants include water-soluble quaternary ammonium compounds of
the form R₄R₅R₆R₇N⁺X⁻, wherein R₄ is alkyl having from 10 to 20, preferably from 12-18
carbon atoms, and R₅, R₆ and R₇ are each C₁ to C₇ alkyl preferably methyl; X⁻ is an
anion, e.g. chloride. Examples of such trimethyl ammonium compounds include C₁₂₋₁₄
alkyl trimethyl ammonium chloride and cocalkyl trimethyl ammonium methosulfate.
[0034] Specific preferred surfactants for use herein include: sodium linear C₁₁-C₁₃ alkylbenzene
sulfonate; alpha-olefin sulphonates; triethanolammonium C₁₁-C₁₃ alkylbenzene sulfonate;
alkyl sulfates, (tallow, coconut, palm, synthetic origins, e.g. C₄₅, etc.); sodium
alkyl sulfates; methyl ester sulphonate; sodium coconut alkyl glyceryl ether sulfonate;
the sodium salt of a sulfated condensation product of a tallow alcohol with about
4 moles of ethylene oxide; the condensation product of a coconut fatty alcohol with
about 6 moles of ethylene oxide; the condensation product of tallow fatty alcohol
with about 11 moles of ethylene oxide; the condensation of a fatty alcohol containing
from about 14 to about 15 carbon atoms with about 7 moles of ethylene oxide; the condensation
product of a C₁₂-C₁₃ fatty alcohol with about 3 moles of ethylene oxide; 3-(N,N-dimethyl-N-coconutalkylammonio)-2-hydroxypropane-1-sulfonate;
3-(N,N-dimethyl-N-coconutalkylammonio)-propane-1-sulfonate; 6- (N-dodecylbenzyl-N,N-dimethylammonio)
hexanoate; dodecyldimethylamine oxide; coconutalkyldimethylamine oxide; and the water-soluble
sodium and potassium salts of coconut and tallow fatty acids.
The surfactant paste described above is formed into granules by fine dispersion mixing
in the presence of a powder. In the present invention, the surfactant paste is either
intimately mixed with a component which is a free-flowing mixture of a hydrophobic
silica and a hygroscopic powder comprising a polymer prior to granulation, or said
free-flowing mixture is added directly to the mixer/granulator as one of the powder
components of the granulation step.
The hydrophobic silica which is present at a level of from 0.5% to 10% of the component
is a highly dispersed amorphous silicon dioxide. It is commercially available in many
forms. Most commonly silica has a tapped density of from 50 g/l to 120 g/l. The specific
surface area of the particles ranges from 25 square metres per gram to 800 square
metres per gram.
The surface of silica particles can be chemically modified to change their behaviour
with respect to water. For example,silica particles may be treated with organosilanes
to make the particles predominantly hydrophobic. It has been found that silicas must
be hydrophobised to be useful in the present invention.
In commercial practice, silica is usually prepared by one of two techniques; either
by precipitation or by high temperature flame hydrolysis. Precipitated silicas generally
have an agglomerate size of from 3 micrometers to 100 micrometers, whereas fumed silicas
(made by flame hydrolysis) usually have primary particles which are generally spherical
and have an average diameter of from 7nm to 40nm. Fumed silicas having an average
primary particle size of from 7 to 25 nanometers are preferred in the present invention.
Examples of silicas which are particularly useful in the present invention include
those supplied by Degussa AG, Frankfurt, Germany under the Trade Name "Aerosil". Aerosil
R972 has been found to be particularly useful. This silica is a hydrophobic, fumed
silica which has a specific surface area of about 110 square metres per gram and an
average primary particle size of 16 nanometers.
The other essential feature of the powder is a hygroscopic powder which comprises
a polymer. By hygroscopic it is meant that the powder shows more than 50% moisture
uptake at 80% relative humidity at 25°C. To measure this a 3 gram sample of the powder,
having an average particle size of 250 micrometers, is placed on an 80mm diameter
petri dish. The sample is dried in a vacuum oven at 40°C for 48 hours, and the dry
weight recorded. The sample is then placed in a relative humidity and temperature
control unit. (That is, any sample chamber which has controllable % relative humidity
(80+/-2%) and temperature (25+/-1°C)). The unit is set at 80% relative humidity and
25°C for at least 8 hours. The sample weight is then recorded again.
For the purposes of the present invention a powder which absorbs more than 50% of
its dry weight at 80% relative humidity and 25°C is considered to be hygroscopic.
The powder may consist exclusively of a polymer, or, alternatively, the powder may
further comprise other detergent ingredients such as surfactants, builders (especially
zeolites) etc. The powder may be prepared by any suitable means including spray drying
of an aqueous solution or slurry of the powder components. One particularly preferred
method is spray drying using a two-fluid nozzle, the process of which is described
in more detail below.
Polymers which are particularly useful as components of the hygroscopic powder of
the present invention include 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), polyvinyl pyrrolidone, polyethylene
glycol, polyaspartate, 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.
Most preferred are 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.
It is a further feature of the present invention that the hygroscopic powder and the
hydrophobic silica are thoroughly premixed before the granulation step with the surfactant
paste. A process for this is described in more detail below.
Optionally other powders may be used in the process of granulating the surfactant
paste. Examples of suitable powders will be described below in more detail.
[0035] The detergent compositions herein can contain crystalline aluminosilicate ion exchange
material of the formula
Na
z[(AlO₂)
z·(SiO₂)
y]·xH₂O
wherein z and y are at least about 6, the molar ratio of z to y is from about 1.0
to about 0.4 and z is from about 10 to about 264. Amorphous hydrated aluminosilicate
materials useful herein have the empirical formula
M
z(zAlO₂·ySiO₂)
wherein M is sodium, potassium, ammonium or substituted ammonium, z is from about
0.5 to about 2 and y is 1, said material having a magnesium ion exchange capacity
of at least about 50 milligram equivalents of CaCO₃ hardness per gram of anhydrous
aluminosilicate. Hydrated sodium Zeolite A with a particle size of from about 1 to
10 microns is preferred.
[0036] The aluminosilicate ion exchange builder materials herein are in hydrated form and
contain from about 10% to about 28% of water by weight if crystalline, and potentially
even higher amounts of water if amorphous. Highly preferred crystalline aluminosilicate
ion exchange materials contain from about 18% to about 22% water in their crystal
matrix. The crystalline aluminosilicate ion exchange materials are further characterized
by a particle size diameter of from about 0.1 micron to about 10 microns. Amorphous
materials are often smaller, e.g., down to less than about 0.01 micron. 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 aluminosilicate ion exchange materials
herein are usually further characterized by their calcium ion exchange capacity, which
is at least about 200 mg equivalent of CaCO₃ 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 aluminosilicate ion exchange materials herein
are still further characterized by their calcium ion exchange rate which is at least
about 2 grains Ca⁺⁺/gallon/minute/gram/gallon of aluminosilicate (anhydrous basis),
and generally lies within the range of from about 2 grains/gallon/minute/gram/gallon
to about 6 grains/gallon/minute/gram/gallon, 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.
[0037] The amorphous aluminosilicate ion exchange materials usually have a Mg⁺⁺ exchange
of at least about 50 mg eq. CaCO₃/g (12 mg Mg⁺⁺/g) and a Mg⁺⁺ exchange rate of at
least about 1 grain/gallon/minute/gram/gallon. Amorphous materials do not exhibit
an observable diffraction pattern when examined by Cu radiation (1.54 Angstrom Units).
[0038] Aluminosilicate ion exchange materials useful in the practice of this invention are
commercially available. The aluminosilicates useful in this invention can be crystalline
or amorphous 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. Preferred synthetic crystalline aluminosilicate ion exchange materials
useful herein are available under the designations Zeolite A, Zeolite B, and Zeolite
X. In an especially preferred embodiment, the crystalline aluminosilicate ion exchange
material has the formula
Na₁₂[(AlO₂)₁₂(SiO2)₁₂]·xH₂O
wherein x is from about 20 to about 30, especially about 27 and has a particle size
generally less than about 5 microns.
[0039] 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.
[0040] 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.
[0041] 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 polyhydroxysulfonates. Preferred
are the alkali metal, especially sodium, salts of the above.
[0042] 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.
[0043] Examples of nonphosphorus, inorganic builders are sodium and potassium carbonate,
bicarbonate, sesquicarbonate, tetraborate decahydrate, and silicate having a molar
ratio of SiO₂ to alkali metal oxide of from about 0.5 to about 4.0, preferably from
about 1.0 to about 2.4.
[0044] As mentioned above powders normally used in detergents such as zeolite, carbonate,
silica, silicate, citrate, phosphate, perborate, etc. and process acids such as starch
and sugars, can be used in preferred embodiments of the present invention. Optionally,
other components may be added at any one of the stages of the process of the present
invention, or they may be mixed with or sprayed on to the granular detergents of the
present invention.
Another optional detergent composition ingredient is a suds suppressor, exemplified
by silicones, and silica-silicone mixtures. Silicones can be generally represented
by alkylated polysiloxane materials while silica is normally used in finely divided
forms, exemplified by silica aerogels and xerogels and hydrophobic silicas of various
types. These materials can be incorporated as particulates in which the suds suppressor
is advantageously releasably incorporated in a water-soluble or water-dispersible,
substantially non-surface-active detergent-impermeable carrier. Alternatively the
suds suppressor can be dissolved or dispersed in a liquid carrier and applied by spraying
on to one or more of the other components.
As mentioned above, useful silicone suds controlling agents can comprise a mixture
of an alkylated siloxane, of the type referred to hereinbefore, and solid silica.
Such mixtures are prepared by affixing the silicone to the surface of the solid silica.
A preferred silicone suds controlling agent is represented by a hydrophobic silanated
(most preferably trimethyl-silanated) silica having a particle size in the range from
10 nanometers to 20 nanometers and a specific surface area above 50 m²/g, intimately
admixed with dimethyl silicone fluid having a molecular weight in the range from about
500 to about 200,000 at a weight ratio of silicone to silanated silica of from about
1:1 to about 1:2.
A preferred silicone suds controlling agent is disclosed in Bartollota et al. US Patent
3,933,672. Other particularly useful suds suppressors are the self-emulsifying silicone
suds suppressors, described in German Patent Application DTOS 2,646,126 published
April 28, 1977. An example of such a compound is DC0544, commercially available from
Dow Corning, which is a siloxane/glycol copolymer.
The suds suppressors described above are normally employed at levels of from 0.001%
to 0.5% by weight of the composition, preferably from 0.01% to 0.1% by weight.
The preferred methods of incorporation comprise either application of the suds suppressors
in liquid form by spray-on to one or more of the major components of the composition
or alternatively the formation of the suds suppressors into separate particulates
that can then be mixed with the other solid components of the composition. The incorporation
of the suds modifiers as separate particulates also permits the inclusion therein
of other suds controlling materials such as C₂₀-C₂₄ fatty acids, microcrystalline
waxes and high MWt copolymers of ethylene oxide and propylene oxide which would otherwise
adversely affect the dispersibility of the matrix. Techniques for forming such suds
modifying particulates are disclosed in the previously mentioned Bartolotta et al
US Patent No. 3,933,672.
Another optional ingredient useful in the present invention is one or more enzymes.
Preferred enzymatic materials include the commercially available amylases, neutral
and alkaline proteases, lipases, esterases and cellulases conventionally incorporated
into detergent compositions. Suitable enzymes are discussed in US Patents 3,519,570
and 3,533,139.
The process of fine dispersion mixing or granulation will typically be carried out
in a high speed mixer. The term "fine dispersion mixing and/or granulation", as used
herein, means mixing and/or granulation of the mixture in a fine dispersion mixer
at a blade tip speed of from about 5m/sec. to about 50 m/sec., unless otherwise specified.
The total residence time of the mixing and granulation process is preferably in the
order of from 0.1 to 10 minutes, more preferably 0.1-5 and most preferably 0.2-4 minutes.
The more preferred mixing and granulation tip speeds are about 10-45 m/sec. and about
15-40 m/sec.
[0045] Any apparatus, plants or units suitable for the processing of surfactants can be
used for carrying out the process according to the invention. Suitable apparatus includes,
for example, falling film sulphonating reactors, digestion tanks, esterification reactors,
etc. For mixing/agglomeration any of a number of mixers/agglomerators can be used.
In one preferred embodiment, the process of the invention is continuously carried
out. Especially preferred are mixers of the Fukae
R FS-G series manufactured by Fukae Powtech Kogyo Co., Japan; this apparatus is essentially
in the form of a bowl-shaped vessel accessible via a top port, provided near its base
with a stirrer having a substantially vertical axis, and a cutter positioned on a
side wall. The stirrer and cutter may be operated independently of one another and
at separately variable speeds. The vessel can be fitted with a cooling jacket or,
if necessary, a cryogenic unit.
[0046] Other similar mixers found to be suitable for use in the process of the invention
include Diosna
R V series ex Dierks & Söhne, Germany; and the Pharma Matrix
R ex T K Fielder Ltd., England. Other mixers believed to be suitable for use in the
process of the invention are the Fuji
R VG-C series ex Fuji Sangyo Co., Japan; and the Roto
R ex Zanchetta & Co srl, Italy.
[0047] Other preferred suitable equipment can include Eirich
R, series RV, manufactured by Gustau Eirich Hardheim, Germany; Lödige
R, series FM for batch mixing, series Baud KM for continuous mixing/agglomeration,
manufactured by Lödige Machinenbau GmbH, Paderborn Germany; Drais
R T160 series, manufactured by Drais Werke GmbH, Mannheim Germany; and Winkworth
R RT 25 series, manufactured by Winkworth Machinery Ltd., Berkshire, England.
[0048] The Littleford Mixer, Model #FM-130-D-12, with internal chopping blades and the Cuisinart
Food Processor, Model #DCX-Plus, with 7.75 inch (19.7 cm) blades are two examples
of suitable mixers. Any other mixer with fine dispersion mixing and granulation capability
and having a residence time in the order of 0.1 to 10 minutes can be used. The "turbine-type"
impeller mixer, having several blades on an axis of rotation, is preferred. The invention
can be practiced as a batch or a continuous process.
The preferred operating temperatures for the agglomeration step should also be as
low as possible since this leads to a higher surfactant concentration in the finished
particle. Preferably the temperature during the agglomeration is less than 100°C,
more preferably between 10 and 90°C, and most preferably between 20 and 80°C. Lower
operating temperatures useful in the process of the present invention may be achieved
by a variety of methods known in the art such as nitrogen cooling, cool water jacketing
of the equipment, addition of solid CO₂, and the like; with a preferred method being
solid CO₂, and the most preferred method being nitrogen cooling.
The granules formed in the high speed mixer may still have a higher moisture content
than desired. In this case the desired moisture content of the free flowing granules
of this invention can be adjusted to levels adequate for the intended application
by drying in conventional powder drying equipment such as fluid bed dryers. If a hot
air fluid bed dryer is used, care must be exercised to avoid degradation of heat sensitive
components of the granules. It is also advantageous to have a cooling step prior to
large scale storage. This step can also be done in a conventional fluid bed operated
with cool air. The drying/cooling of the agglomerates can also be done in any other
equipment suitable for powder drying such as rotary dryers, etc.
[0049] For detergent applications, the final moisture of the agglomerates needs to be maintained
below levels at which the agglomerates can be stored and transported in bulk. The
exact moisture level depends on the composition of the agglomerate but is typically
achieved at levels of 1-8% free water (i.e. water not associated to any crystalline
species in the agglomerate) and most typically at 2-4%.
Further details of the preferred process of the present invention are given below.
A preferred process for the preparation of the hygroscopic powder is by spray drying.
A most preferred process uses a two fluid nozzle or spinning disk. These nozzles are
particularly useful to make polymer containing granules for use in the present invention,
wherein the concentrated polymer-containing slurry or solution has a high viscosity
and/or a non-Newtonian rheology. Such a slurry is difficult to spray dry through a
conventional pressure nozzle.
Suitable two fluid nozzles and disks are supplied by Delavan, and described in their
"Spray Drying Manual" and by Spraying Systems Co., and described in their Technical
Manual No. 402.
The atomisation in two-fluid nozzles is derived from energy in compressed air, gas
or pressurised steam. Preferably air-atomising nozzles are used. The atomisation in
spinning disks is derived from the kinetic energy of the disk on to which the slurry
or solution is sprayed.
The slurry or solution may comprise other detergent ingredients, such as those described
herein, as well as polymer. One preferred composition is polymer and aluminosilicate,
especially zeolite A. Compositions of this type, as well as processes for making them
have been described in DE 33 16 513, published on 8th November, 1984.
When the hygroscopic powder has been prepared, it is the necessary to coat the surface
with hydrophobic silica. Suitable hydrophobic silicas have been described above.
The hygroscopic powders can be added placed in a low shear mixer or rotating drum.
The hydrophobic silica can then be added to the drum or mixer while it is in motion.
The hydrophobic silica coats the hygroscopic powder and makes the particles free flowing.
The flow aid creates a hydrophobic layer which protects against moisture. The invention
can be practised as a batch or a continuous process. Alternatively, another process
which is suited to the present invention is that of fluidised bed coating. In a fluidised
bed process the solid particles are largely separate from one another, i.e. in a fluidised
state, and can therefore be effectively coated by the hydrophobic silica.
The extruder fulfils the functions of pumping and mixing the viscous surfactant paste
on a continuous basis. A basic extruder consists of a barrel with a smooth inner cylindrical
surface. Mounted within this barrel is the extruder screw. There is an inlet port
for the high active paste which, when the screw is rotated, causes the paste to be
moved along the length of the barrel.
The detailed design of the extruder allows various functions to be carried out. Firstly
additional ports in the barrel may allow other ingredients, including the chemical
structuring agents to be added directly into the barrel. Secondly a vacuum pump and
a seal around the shaft of the screw allows a vacuum to be drawn which enables the
moisture level to be reduced. Thirdly means for heating or cooling may be installed
in the wall of the barrel for temperature control. Fourthly, careful design of the
extruder screw promotes mixing of the paste both with itself and with other additives.
A preferred extruder is the twin screw extruder. This type of extruder has two screws
mounted in parallel within the same barrel, which are made to rotate either in the
same direction (co-rotation) or in opposite directions (counter-rotation). The co-rotating
twin screw extruder is the most preferred piece of equipment for use in this invention.
An extruder is particularly useful in a preferred embodiment of the present invention
because the hygroscopic powder/hydrophobic silica can be added to the surfactant paste
via an inlet port in the extruder and can be considered as chemical structuring agents.
The extruder helps to ensure thorough and intimate mixing of the paste and the powder.
In this embodiment of the invention the extruder conveys the conditioned paste which
now comprises polymer and hydrophobic silica into the mixer where fine dispersion
and granulation takes place. Suitable mixers have been defined above.
[0050] Suitable twin screw extruders for use in the present invention include those supplied
by : APV Baker, (CP series); Werner and Pfleiderer, (Continua Series); Wenger, (TF
Series); Leistritz, (ZSE Series); and Buss, (LR Series).
[0051] The extruder allows the paste to be conditioned by moisture and temperature reduction.
Moisture may be removed under vacuum, preferably between 0 mmHg (gauge) and -55 mmHg
(gauge), (0 - 7.3 kPa below atmospheric pressure).
[0052] Temperature may be reduced by the addition of solid carbon dioxide or liquid nitrogen
directly into the extruder barrel. Preferably liquid nitrogen is used at up to 30%
by weight of the paste.
EXAMPLES
[0053] In these examples the following abbreviations have been used:
C25E3 C12-15 alkyl ethoxylate, with an average of 3 ethoxy groups per molecule
GA N-methyl glucamide
PVP Polyvinyl pyrrolidone
Example 1
[0054] An aqueous surfactant paste was prepared comprising: 62.5% by weight sodium alkyl
sulphate having substantially C14 and C15 alkyl chains;
15.5% by weight sodium alkyl ester sulphate having substantially C13 to C15 alkyl
chains and an average of 3 ethoxy groups per molecule;
17% by weight of water and the balance being mainly comprised of unreacted alcohol
and sulphates.
A powder premix was prepared by mixing the sodium salt of a co-polymer of maleic and
acrylic acid with 2% by weight of hydrophobic silica (Aerosil R972, trade name, supplied
by Degussa) in a Loedige FM130D (trade name) mixer for 30 seconds.
The aqueous surfactant paste and the premixed co-polymer / hydrophobic silica were
then intimately mixed in a twin screw extruder with a barrel in 6 sections (manufactured
by Werner & Pfleiderer, C58).The resulting viscous paste was then placed in a Loedige
FM130D (trade name) batch ploughshare mixer containing a mixture of 2 parts zeolite
A to 1 part finely divided light carbonate. The mixer is operated until granulation
takes place.
The resulting agglomerates were transferred to a fluid bed drier and then classified
through mesh sieves to remove oversize and fine particles.
The agglomerates formed had a surfactant content of 40% by weight, a polymer level
of 12% by weight, a silica level of 0.24% by weight and an equilibrium relative humidity
level of 10% at room temperature.
The granules formed have excellent flow and handling properties.
Comparative Example 2
[0055] The process of example 1 was repeated, except that the co-polymer of maleic and acrylic
acid was not mixed with 2% of hydrophobic silica. The silica level in the finished
agglomerates was 0%, and the agglomerates after granulation, drying and classification
showed poor handling and flow properties.
Example 3
[0056] An aqueous surfactant paste was prepared comprising:
62.5% by weight sodium alkyl sulphate having substantially C14 and C15 alkyl chains;
15.5% by weight sodium alkyl ester sulphate having substantially C13 to C15 alkyl
chains and an average of 3 ethoxy groups per molecule;
17% by weight of water and the balance being mainly comprised of unreacted alcohol
and sulphates.
A powder premix was prepared by mixing the sodium salt of a co-polymer of maleic and
acrylic acid with 2% by weight of hydrophobic silica (Aerosil R972, trade name, supplied
by Degussa) batchwise in a ribbon blender.
The aqueous surfactant paste and the premixed co-polymer / hydrophobic silica were
then intimately mixed in a twin screw extruder (manufactured by Werner & Pfleiderer,
C170).The resulting viscous paste was extruded directly into a Loedige CB30 (trade
name) high speed mixer containing a mixture of 1 part zeolite A to 1 part finely divided
light carbonate. The mixer operates on a continuous basis and discharges directly
into a Loedige KM (trade name) continuous ploughshare mixer.
The resulting agglomerates were transferred to a fluid bed drier, cooled in a fluid
bed cooler and then classified through mesh sieves to remove oversize and fine particles.
The agglomerates formed had a surfactant content of 40% by weight, a polymer level
of 11.2% by weight, a silica level of 0.22% by weight and an equilibrium relative
humidity level of 10% at room temperature.
The granules formed have excellent flow and handling properties.
Example 4
[0057] An Eirich RVO2 high shear mixer was charged with a mixture of 32 parts Zeolite A
to 32 parts finely divided carbonate. A mixture of 10 parts PVP and 1 part hydrophobic
silica (Aerosil R972, trade name, supplied by Degussa) was premixed and added to the
mixer. 25 parts of a nonionic surfactant paste of containing GA and C25E3 in a 25/75
ratio were also added to the mixer.
The mixer is operated at a speed of 2500 rpm until granulation takes place. The mixer
is then stopped and the agglomerates are cooled in a fluid bed and classified through
mesh sieves. The resulting agglomerates have excellent physical properties including
flowability and have a bulk density of 750 g/l.
Example 5
[0058] The process of example 4 was repeated replacing the 32 parts of carbonate by 32 parts
of finely divided citrate.
Example 6
[0059] This example describes the process in batch mode in a lab scale high shear mixer
(food processor).The sodium salt of the copolymer of maleic and acrylic acid is premixed
with the hydrophobic silica. The mixer is first charged with a mixture of powders
to be used, in this case:
|
percent by weight |
sodium salt of the copolymer of maleic and acrylic acid |
10 |
hydrophobic silica (Aerosil R972) |
1 |
Carbonate |
32 |
Zeolite A |
32 |
total |

|
A nonionic surfactant paste containing a GA/C25E3 mixture at a ratio of 50/50 was
added at 25 percent by weight before starting the mixer. The mixer was then operated
until granulation took place. The mixer was then stopped and the agglomerates were
cooled in a fluid bed and classified through mesh sieves. The resulting agglomerates
had excellent physical properties including flowability and had a bulk density of
700 g/l.