U.S. patent application number 09/142652 was filed with the patent office on 2001-07-26 for modified aluminosilicate.
Invention is credited to APPEL, PETER WILLEM, ARTS, THEODORUS JOHANNES C, LANCELEY, CAROLYN ANGELA, OSINGA, THEO JAN.
Application Number | 20010009895 09/142652 |
Document ID | / |
Family ID | 10790490 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009895 |
Kind Code |
A1 |
APPEL, PETER WILLEM ; et
al. |
July 26, 2001 |
MODIFIED ALUMINOSILICATE
Abstract
A modified aluminosilicate in powder form comprising alkali
metal silicate deposited onto aluninosilicate of the zeolite P type
particles presents increased Liquid Carrying Capacity.
Inventors: |
APPEL, PETER WILLEM; (DC
ROTTERDAM, NL) ; ARTS, THEODORUS JOHANNES C;
(MAASTRICHT, NL) ; LANCELEY, CAROLYN ANGELA;
(CHESTER, GB) ; OSINGA, THEO JAN; (AN CADIER EN
KEER, NL) |
Correspondence
Address: |
PILLSBURY MADISON & SUTRO LLP
1100 NEW YORK AVENUE, N.W.
NINTH FLOOR
WASHINGTON
DC
20005-3918
US
|
Family ID: |
10790490 |
Appl. No.: |
09/142652 |
Filed: |
August 3, 1999 |
PCT Filed: |
March 7, 1997 |
PCT NO: |
PCT/EP97/01208 |
Current U.S.
Class: |
510/315 ;
510/323; 510/466; 510/507; 510/511 |
Current CPC
Class: |
C01B 39/026 20130101;
C11D 3/128 20130101; C11D 3/08 20130101 |
Class at
Publication: |
510/315 ;
510/323; 510/511; 510/466; 510/507 |
International
Class: |
C11D 007/02; C11D
003/02; C11D 001/00; C12S 011/00; C11D 007/42; C11D 009/42; C11D
007/54 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 1996 |
GB |
9605533.0 |
Claims
1. Modified aluminosilicate in powder form comprising alkali metal
silicate deposited onto aluminosilicate of the zeolite P type
particles.
2. Modified aluminosilicate according to claim 1 comprising 65 to
90%, preferably 70 to 87%, most preferably 75 to 85% by weight (on
dry basis) of aluminosilicate of the zeolite P type and 1 to 20%,
preferably 3 to 15%, most preferably 5 to 10% by weight (on dry
basis) of alkali metal silicate.
3. Modified aluminosilicate according to claim 2 wherein the
(aluminosilicate of the zeolite P type/alkali metal silicate)
weight ratio on dry basis is within the range of 100/20 to 100/1,
preferably 100/15 to 100/3, more preferably 100/10 to 100/5.
4. Modified aluminosilicate according to any preceding claim
wherein the alkali metal silicate is sodium silicate having a
SiO.sub.2:Na.sub.2O molar ratio of between 1.6 and 4.
5. Modified aluminosilicate according to claims 1 to 3 having an
average weight particle size of 1 .mu.m to 10 .mu.m, preferably
between 1.5 .mu.m and 6 .mu.m, more preferably between 2.5 .mu.m
and 5 .mu.m.
6. Modified aluminosilicate according to claims 1 to 3 having a
CEBC of between 110 and 160 mg CaO/g modified aluminosilicate (on
dry basis), more preferably 130 and 155 mg CaO/g modified
aluminosilicate (on dry basis).
7. Modified aluminosilicate according to claims 1 to 3 further
comprising an effective amount of additive selected from the group
consisting of phosphonates, amino carboxylates, polycarboxylates,
citrates, and mixtures thereof.
8. Modified aluminosilicate according to claims 1 to 3 having a pH
of between 10 and 12.
9. Process for the production of a modified aluminosilicate wherein
to a slurry of aluminosilicate of the zeolite P type, containing 20
to 46% solids, more preferably 30-40% solids, is added an alkali
metal silicate the resulting mixture being further dried.
10. Process according to claim 9 wherein carbon dioxide is
circulated inside the modified aluminosilicate during the drying
process.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a modified aluminosilicate
and more specifically to a modified aluminosilicate of the zeolite
P type particularly useful in detergent compositions.
BACKGROUND OF THE INVENTION
[0002] The usefulness of zeolite P in detergent formulations has
been acknowledged, for example in European Patent Application
0384070 (Unilever).
[0003] The zeolite P class includes a series of synthetic zeolite
phases which may be in cubic configuration (also termed B or
P.sub.c) or tetragonal configuration (also termed P.sub.1) but is
not limited to these forms. The structure and characteristics of
the zeolite P class are given in "Zeolite Molecular Sieves" of
Donald W Breck (published 1974 and 1984 by Robert E Krieger of
Florida USA). The zeolite P class has the typical oxide
formula:
M.sub.{fraction (2/n)}O. Al.sub.2O.sub.3. 1.80-5.00 SiO.sub.2.
5H.sub.2O
[0004] M is an n-valent cation which for this invention is an
alkali-metal, that is lithium, potassium, sodium, cesium or
rubidium with sodium and potassium being preferred and sodium being
the cation normally used in commercial processes.
[0005] Thus sodium may be present as the major cation with another
alkali metal present in a minor proportion to provide a specific
benefit.
[0006] Now, zeolites used in detergents compositions must, on top
of their detergent characteristics such as Calcium Binding
Capacity, Calcium Effective Binding Capacity and Calcium uptake
rate, exhibit other characteristics which render them usable as
builders in concentrated detergents compositions.
[0007] The ability for a builder to be used in such concentrated
formulations relates directly to its Liquid Carrying Capacity also
referred to as Oil Absorption. The higher the Liquid Carrying
Capacity the more concentrated can be the detergents
composition.
[0008] Moreover, whereas in the past powder detergents composition
were produced by spray drying, a new manufacturing processes, known
as non spray drying processes, have been proposed. In these
processes, the Liquid Carrying Capacity of the builder is of even
greater importance.
[0009] Now, it is known that, depending on the drying conditions,
the Liquid Carrying Capacity of certain products can vary within a
great range. For example, the zeolite P disclosed in EP-B-0384070
can have, depending on its drying conditions, a Liquid Carrying
Capacity of from 50-65% to 100-110%, the lower values being reached
with industrial drying conditions such as spray drying, turbo
drying, flash drying or flash-ring drying.
[0010] Therefore, even though the Liquid Carrying Capacity of the
zeolite P disclosed in EP-B-0384070 already enables it to be used
as a builder in concentrated detergent compositions, there is
nevertheless a need for increasing even more the Liquid Carrying
Capacity in case of industrial drying conditions.
[0011] In other respects, even though the addition of silicates in
detergents compositions is particularly useful to avoid corrosion,
to improve bleach stability in the wash and to act as an
anti-redeposition agent, its use in detergent compositions has
dramatically decreased for a series of reasons.
[0012] First of all, the major detergent compositions are still
using zeolite A (such as Doucil P, obtainable from Crosfield ltd.)
as their builder. Now, it is known that when drying together
zeolite A and silicate, large lumps of insoluble materials are
formed something which gives rise to residues on the fabrics.
[0013] Secondly, sodium silicates with a SiO.sub.2:Na.sub.2O molar
ratio of between 1.6 and 3.2 are being avoided for safety reasons
since they are classified as irritant due to their alkalinity.
Silicates with a ratio of 3.3 or above are safe but do not dissolve
easily and with a ratio of below 1.6 they are corrosive. Therefore
there is a need for a new way to introduce alkali metal silicate in
detergent compositions which obviate the above mentioned
problems.
[0014] Now, it has been found that a specific combination of
aluminosilicates of the zeolite P type and alkali metal silicate
can, on the one hand dramatically increase the Liquid Carrying
Capacity of the zeolite while, on the other hand, leading to a
product which is no longer irritant and does not contribute
significantly to the occurrence of residues on fabrics.
[0015] Tests and Definitions
[0016] i) Average weight particle size, d.sub.50
[0017] The quantity "d.sub.50" indicates that 50% by weight of the
particles have a diameter smaller than that figure, and may be
measured using a Sedigraph (Trade Mark), type 5100, ex
Micromeritics.
[0018] ii) pH
[0019] pH measurements were performed by making a 5% dispersion of
zeolite (dry solids basis) in demineralised water, followed by
measurement with a Orion EA940 ion analyzer, using a Orion 9173b
pH-electrode.
[0020] iii) CEBC (Calcium Effective Binding Capacity)
[0021] The CEBC was measured in the presence of a background
electrolyte to provide a realistic indicator of calcium ion uptake
in a wash liquor environment. A sample of each zeolite was first
equilibrated to constant weight over a saturated sodium chloride
solution and the water content measured. Each equilibrated sample
was dispersed in water (1 cm.sup.3) in an amount corresponding to 1
g dm.sup.-3 (dry), and the resulting dispersion (1 cm.sup.3) was
injected into a stirred solution, consisting of 0.01 M NaCl
solution (50 cm.sup.3) and 0.05M CaCl.sub.2 (3.923 cm.sup.3),
therefore producing a solution of total volume 54.923 cm.sup.3.
This corresponded to a concentration of 200 mg CaO per liter, i.e.
just greater than the theoretical maximum amount (197 mg) that can
be taken up by a zeolite of Si:Al ratio 1.00. The change in
Ca.sup.2+ ion concentration was measured by using a Ca.sup.2+ ion
selective electrode, the final reading being taken after 15
minutes. The temperature was maintained at 25.degree. C.
throughout. The Ca.sup.2+ ion concentration measured was subtracted
from the initial concentration, to give the effective calcium
binding capacity of the zeolite sample as mg CaO/g zeolite (on dry
basis).
[0022] iv) LCC (Liquid Carrying Capacity
[0023] This was determined on the basis of the ASTM spatula rub-out
method (American of Test Material Standards D281). The test is
based on the principle of mixing nonionic (Synperonic A3, available
from ICI) with the particulate zeolite by rubbing with a spatula on
a smooth surface until a stiff putty like paste is formed which
will not break or separate when it is cut with the spatula. The
weight of nonionic used is then put into the equation: 1 LCC = g
nonionic absorbed wt of zeolite ( gms ) .times. 100 = g nonionic /
100 g zeolite
[0024] v) Grit
[0025] Grit is defined here as the percentage of particles which
are left behind on a 45 .mu.m sieve. Zeolite is slurried with water
in a beaker, ultrasonically treated for 15 minutes and next placed
in the sieving machine (Mocker). This machine is subsequently
flushed with water (water pressure 4 bar) for a certain period of
time.
[0026] The sieve is removed from the machine and dried in an oven
(90.degree. C., 15 min.) and the amount of residue determined. 2
grit ( % ) = residue wt of zeolite ( dry basis )
[0027] General Description of the Invention
[0028] It is a first object of the present invention to provide a
modified aluminosilicate in powder form comprising alkali metal
silicate deposited onto aluminosilicate of the zeolite P type
particles.
[0029] Preferably, the aluminosilicate of the zeolite P type has a
silicon to aluminium ratio not greater than 1.33, preferably not
greater than 1.07. Preferably also it has a Calcium Effective
Binding Capacity of at least 140 mg CaO/g zeolite (on dry
basis).
[0030] By having the alkali metal silicate deposited onto the
aluminosilicate, a completely homogeneous mixture of the two
products is achieved something which means that, when introduced
into a detergent composition the two products are evenly
distributed and that there is no local variation in the
aluminosilicate/alkali metal silicate weight ratio in the detergent
composition.
[0031] The modified aluminosilicate according to the present
invention has a pH of between 10 and 12. This relatively low
alkalinity renders the product not irritant. Moreover, the fact
that the alkali metal silicate and the aluminosilicate are evenly
distributed means, particularly, that no pH variation can occur due
to local variation in the aluminosilicate/alkali metal silicate
weight ratio something which renders the modified aluminosilicate
according to the present invention particularly safe.
[0032] Typically, the modified aluminosilicate in powder form
according to the present invention contains 0% to 25% water,
preferably not more than 12% by weight.
[0033] Preferably, the modified aluminosilicate comprises 65 to
90%, preferably 70 to 87%, most preferably 75 to 85% by weight (on
dry basis) of aluminosilicate of the zeolite P type and 1 to 20%,
preferably 3 to 15%, most preferably 5 to 10% by weight (on dry
basis) of alkali metal silicate. More preferably the
(aluminosilicate of the zeolite P type/alkali metal silicate)
weight ratio is within the range of 100/20 to 100/1, preferably
100/15 to 100/3, more preferably 100/10 to 100/5.
[0034] Also preferably, the alkali metal silicate is sodium
silicate having a SiO.sub.2:Na.sub.2O molar ratio of between 1.6
and 4.
[0035] Preferably also the modified aluminosilicate according to
the present invention has an average weight particle size of 1
.mu.m to 10 .mu.m, preferably between 1.5 .mu.m and 6 .mu.m, more
preferably between 2.5 .mu.m and 5 .mu.m. Such a particle size
distribution contributes to the avoidance of residues on
fabrics.
[0036] The modified aluminosilicate according to the present
invention exhibits good detergent characteristics, the CEBC being
typically between 110 and 160 mg CaO/g modified aluminosilicate (on
dry basis), more preferably between 130 and 155 mg CaO/g modified
aluminosilicate (on dry basis).
[0037] Various other additives can be added to the modified
aluminosilicate of the invention and it can further contain an
effective amount of additive selected from the group consisting of
phosphonates, amino carboxylates, polycarboxylates, citrates, and
mixtures thereof, usually at levels from 0.3% to 5.0% by weight of
said modified aluminosilicate (on dry basis).
[0038] The modified aluminosilicate according to the present
invention can be further granulated according to standard
granulating/agglomerating processes.
[0039] It is a second object of the present invention to provide a
process for the production of a modified aluminosilicate wherein to
a slurry of aluminosilicate of the zeolite P type, containing 20 to
46% solids, more preferably 30-40% solids, is added an alkali metal
silicate, the resulting mixture being further dried.
[0040] Preferably, the alkali metal silicate is sodium silicate
having a SiO.sub.2:Na.sub.2O molar ratio of between 1.6 and 4.
[0041] Preferably also, alkali metal silicate is added as a
solution but could also be in powder form.
[0042] Preferably the alkali metal silicate solution is added to a
slurry of undried zeolite P obtained for example as in example 11
of EP-A-565,364. By undried zeolite P, it is understood a zeolite P
as obtained after washing and filtering but before drying.
[0043] It has been noted that, when fast drying the filter cake
obtained in the process disclosed in EP-A-565,364, the average
particle size of the zeolite P decreases from about 3 .mu.m to
about 1 .mu.m. Now, if at least 3-4% sodium silicate is added
before drying, the average particle size of the product remains
unchanged. This behaviour leads to the surprising result that, with
a higher particle size, the Liquid Carrying Capacity of the end
product (modified alumino silicate of the invention) is increased
whereas all the prior art teaches that Liquid Carrying Capacity is
increased when particle size is decreased.
[0044] Upon milling of this material, the Liquid Carrying Capacity
of the modified aluminosilicate according to the present invention
can be reduced.
[0045] Preferably, carbon dioxide is introduced during the drying
process. By doing so, the alkali metal silicate is, at least
partially, neutralized.
[0046] The modified aluminosilicate according to the present
invention may be incorporated in detergent compositions of all
physical types, for example, powders, liquids, gels and solid bars,
at the levels normally used for detergency builders.
[0047] The modified aluminosilicate material of the invention may
be used as a sole detergency builder, or it may be used in
conjunction with other builder materials such zeolite A or zeolite
P. As well as the crystalline aluminosilicate builders already
mentioned, other inorganic or organic builders may be present.
Inorganic builders that may be present include sodium carbonate,
amorphous aluminosilicates, and phosphate builders, for example,
sodium orthophosphate, pyrophosphate and tripolyphosphate.
[0048] The total amount of detergency builder in the composition
will suitably range from 20 to 80% by weight, and this may be
constituted wholly or partially by the modified aluminosilicate
material of the invention. The modified aluminosilicate material of
the invention may if desired be used in combination with other
aluminosilicates, for example, zeolite A. The total amount of
aluminosilicate material in the composition may, for example, range
from about 5 to 80% by weight preferably from 10 to 60% by
weight.
[0049] Organic builders that may additionally be present include
polycarboxylate polymers such as polyacrylates and acrylic/maleic
copolymers; monomeric polycarboxylates such as citrates,
gluconates, oxydisuccinates, glycerol mono-, di- and trisuccinates,
carboxymethyloxysuccinates, carboxymethyloxymalonates,
dipicolinates, hydroxyethyliminodiacetates, alkyl- and
alkenylmalonates and succinates; and sulphonated fatty acid
salts.
[0050] Especially preferred organic builders are citrates, suitably
used in amounts of from 5 to 30 wt %, preferably from 10 to 25 wt
%; and acrylic polymers, more especially acrylic/maleic copolymers,
suitably used in amounts of from 0.5 to 15 wt %, preferably from 1
to 10 wt %.
[0051] Builders, both inorganic and organic, are preferably present
in alkali metal salt, especially sodium salt, form.
[0052] The modified aluminosilicate of the invention is of especial
applicability to detergent compositions containing no, or reduced
levels of, inorganic phosphate builders such as sodium
tripolyphosphate, orthophosphate and pyrophosphate.
[0053] Detergent compositions containing the modified
aluminosilicate of the invention will also contain, as essential
ingredients, one or more detergent-active compounds which may be
chosen from soap and non-soap anionic, cationic, nonionic,
amphoteric and zwitterionic detergent-active compounds, and
mixtures thereof. Many suitable detergent-active compounds are
available and are fully described in the literature, for example,
in "Surface-Active Agents and Detergents", Volumes I and II, by
Schwartz, Perry and Berch.
[0054] The preferred detergent-active compounds that can be used
are soaps and synthetic non-soap anionic and nonionic
compounds.
[0055] Anionic surfactants are well-known to those skilled in the
art. Examples include alkylbenzene sulphonates, particularly linear
alkylbenzene sulphonates having an alkyl chain length of
C.sub.8-C.sub.15; primary and secondary alkylsulphates,
particularly C.sub.8-C.sub.15 primary alkyl sulphates; alkyl ether
sulphates; olefin sulphonates; alkyl xylene sulphonates; dialkyl
sulphosuccinates; and fatty acid ester sulphonates. Sodium salts
are generally preferred.
[0056] Nonionic surfactants that may be used include the primary
and secondary alcohol ethoxylates, especially the C.sub.8-C.sub.20
aliphatic alcohols ethoxylated with an average of from 1 to 20
moles of ethylene oxide per mole of alcohol, and more especially
the C.sub.10-C.sub.15 primary and secondary aliphatic alcohols
ethoxylated with an average of from 1 to 10 moles of ethylene oxide
per mole of alcohol. Non-ethoxylated nonionic surfactants include
alkylpolyglycosides, glycerol monoethers, and polyhydroxyamides
(glucamide).
[0057] The choice of detergent-active compound (surfactant), and
the amount present, will depend on the intended use of the
detergent composition. For example, for machine dishwashing a
relatively low level of a low-foaming nonionic surfactant is
generally preferred. In fabric washing compositions, different
surfactant systems may be chosen, as is well known to the skilled
formulator, for handwashing products and for products intended for
use in different types of washing machine.
[0058] The total amount of surfactant present will also depend on
the intended end use and may be as low as 0.5 wt %, for example, in
a machine dishwashing composition, or as high as 60 wt %, for
example, in a composition for washing fabrics by hand. In
compositions for machine washing of fabrics, an amount of from 5 to
40 wt % is generally appropriate.
[0059] Detergent compositions suitable for use in most automatic
fabric washing machines generally contain anionic non-soap
surfactant, or nonionic surfactant, or combinations of the two in
any ratio, optionally together with soap.
[0060] Anionic surfactants, soaps and higher-ethoxylated nonionic
surfactants may generally be included in the base powder.
Lower-ethoxylated surfactants may more suitably be post-added.
[0061] Detergent compositions containing the modified
alumino-silicate according to the invention may also suitably
contain a bleach system. The invention is especially concerned with
compositions containing peroxy bleach compounds capable of yielding
hydrogen peroxide in aqueous solution, for example inorganic or
organic peroxyacids, and inorganic persalts such as the alkali
metal perborates, percarbonates, perphosphates, persilicates and
persulphates. As indicated above, the invention is more especially
concerned with compositions containing sodium percarbonate.
[0062] Bleach ingredients are invariably postdosed.
[0063] The sodium percarbonate may have a protective coating
against destabilisation by moisture. Sodium percarbonate having a
protective coating comprising sodium metaborate and sodium silicate
is disclosed in GB 2 123 044B (Kao).
[0064] The peroxy bleach compound, for example sodium percarbonate,
is suitably present in an amount of from 5 to 35 wt %, preferably
from 10 to 25 wt %.
[0065] The peroxy bleach compound, for example sodium percarbonate,
may be used in conjunction with a bleach activator (bleach
precursor) to improve bleaching action at low wash temperatures.
The bleach precursor is suitably present in an amount of from 1 to
8 wt %, preferably from 2 to 5 wt %.
[0066] Preferred bleach precursors are peroxycarboxylic acid
precursors, more especially peracetic acid precursors and
peroxybenzoic acid precursors; and peroxycarbonic acid precursors.
An especially preferred bleach precursor suitable for use in the
present invention is N,N,N',N'-tetracetyl ethylenediamine
(TAED).
[0067] A bleach stabiliser (heavy metal sequestrant) may also be
present. Suitable bleach stabilisers include ethylenediamine
tetraacetate (EDTA) and the polyphosphonates such as Dequest (Trade
Mark), EDTMP.
[0068] Other materials that may be present in detergent
compositions containing the modified aluminosilicate of the
invention such as alkali metal, preferably sodium, carbonate, in
order to increase detergency and ease processing. Sodium carbonate
may suitably be present in amounts ranging from 1 to 60 wt %,
preferably from 2 to 40 wt %. However, compositions containing
little or no sodium carbonate are also within the scope of the
invention. Sodium carbonate may be included in the base powder, or
postdosed, or both.
[0069] Powder flow may be improved by the incorporation of a small
amount of a powder structurant, for example, a fatty acid (or fatty
acid soap), a sugar, an acrylate or acrylate/maleate polymer, in
the base powder. A preferred powder structurant is fatty acid soap,
suitably present in an amount of from 1 to 5 wt %.
[0070] Other materials that may be present in detergent
compositions of the invention include antiredeposition agents such
as cellulosic polymers; soil release polymers; fluorescers;
inorganic salts such as sodium sulphate; lather control agents or
lather boosters as appropriate; proteolytic and lipolytic enzymes;
dyes; coloured speckles; perfumes; foam controllers; and fabric
softening compounds.
[0071] Detergent compositions containing the modified
aluminosilicate of the invention may be prepared by any suitable
method. Detergent powders can suitably be prepared by spray-drying
a slurry of compatible heat-insensitive components, and then
spraying on or postdosing those ingredients unsuitable for
processing via the slurry. Detergent compositions containing the
modified aluminosilicate of the invention are preferably prepared
by non-spray-drying (non-tower) processes. The base powder is
prepared by mixing and granulation, and other ingredients
subsequently admixed (postdosed).
[0072] The base powder may suitably be prepared using a high-speed
mixer/granulator. Processes using high-speed mixer/ granulators are
disclosed, for example, in EP 340 013A, EP 367 339A, EP 390 251A
and EP 420 317A (Unilever).
[0073] Specific Description of the Invention
[0074] The present invention will be further described in the
following examples.
EXAMPLE 1
[0075] A zeolite P obtained according to example 11 of EP-A-565,364
was produced. Before drying, but after washing and filtering to 36%
dry solids, to the zeolite slurry was added a sodium silicate
solution (SiO.sub.2:Na.sub.2O molar ratio of 2) (43% dry solids) to
reach a zeolite P/sodium silicate weight ratio of 10:1 (on dry
basis). The obtained slurry was mixed well and subsequently dried
in a VOMM dryer (obtainable from VOMM Impianti) using direct heated
air (CO.sub.2 content of the air appr. 2.2 weight%) to 90% dry
solids.
EXAMPLE 2
[0076] The same recipe as in example 1 was used except that the
zeolite P/sodium silicate weight ratio of the end slurry (after
addition of sodium silicate) was 100:7.5 (on dry basis).
EXAMPLE 3
[0077] A zeolite P obtained according to example 11 of EP-A-565,364
was produced. Before drying, but after washing and filtering to 35%
dry solids, to the zeolite slurry was added a sodium silicate
solution (SiO.sub.2:Na.sub.2O molar ratio of 2) (43% dry solids) to
reach a zeolite P/sodium silicate weight ratio of 10:1 (on dry
basis). This slurry was filtered to 40.9% dry solids (d.s.).
[0078] The obtained filtercake was next mixed with a polymer
solution (Narlex MA340, ex National Starch, 40% d.s.) to reach a
sodium silicate/polymer weight ratio of 20:2:1.
[0079] The obtained material was subsequently dried in a lab fluid
bed dryer (make Retsch) to 90% d.s..
EXAMPLE 4
[0080] A zeolite P obtained according to example 11 of EP-A-565,364
was produced. Before drying, but after washing and filtering to 35%
dry solids, to the zeolite slurry was added a sodium silicate
solution (SiO.sub.2:Na.sub.2O molar ratio of 2) (43% dry solids) to
reach a zeolite P/sodium silicate weight ratio of 100:8 (on dry
basis). This slurry was filtered to 39.8% d.s..
[0081] The obtained filtercake was next mixed with a polymer
solution (Narlex MA340, ex National Starch, 40% d.s.) to reach a
sodium silicate/polymer weight ratio of 100:8:4.
[0082] The obtained material was subsequently dried in a lab fluid
bed dryer (make Retsch) to 90% d.s..
[0083] The products obtained in examples 1 to 4 had the following
characteristics.
1 Exp. 1 Exp. 2 Exp. 3 Exp. 4 d.sub.50 (.mu.m) 3.12 2.8 2.8 2.8 pH
11.3 11.1 11.7 11.7 CEBC 134 142 137 131 LCC (%) 83 82 72 73 Grit
(%) 0.27 0.13 0.01 0.01
* * * * *