Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Clay or inorganic aluminosilicate salt component
Reexamination Certificate
1999-08-03
2002-09-10
Kopec, Mark (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Clay or inorganic aluminosilicate salt component
C510S511000, C510S466000, C510S315000, C510S323000
Reexamination Certificate
active
06448218
ABSTRACT:
FIELD OF THE INVENTION
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
The usefulness of zeolite P in detergent formulations has been acknowledged, for example in European Patent Application 0384070 (Unilever).
The zeolite P class includes a series of synthetic zeolite phases which may be in cubic configuration (also termed B or P
c
) or tetragonal configuration (also termed P
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
{fraction (2
)}
O. Al
2
O
3
. 1.80-5.00 SiO
2
. 5H
2
O
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.
Thus sodium may be present as the major cation with another alkali metal present in a minor proportion to provide a specific benefit.
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.
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.
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.
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.
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.
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.
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.
Secondly, sodium silicates with a SiO
2
:Na
2
O 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.
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.
Tests and Definitions
i) Average weight particle size, d
50
The quantity “d
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.
ii) pH
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.
iii) CEBC (Calcium Effective Binding Capacity)
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
3
) in an amount corresponding to 1 g dm
−3
(dry), and the resulting dispersion (1 cm
3
) was injected into a stirred solution, consisting of 0.01 M NaCl solution (50 cm
3
) and 0.05M CaCl
2
(3.923 cm
3
), therefore producing a solution of total volume 54.923 cm
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
2+
ion concentration was measured by using a Ca
2+
ion selective electrode, the final reading being taken after 15 minutes. The temperature was maintained at 25° C. throughout. The Ca
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).
iv) LCC (Liquid Carrying Capacity
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:
LCC
=
g
nonionic
absorbed
wt
of
zeolite
(
gms
)
×
100
=
g
nonionic
/
100
g
zeolite
v) Grit
Grit is defined here as the percentage of particles which are left behind on a 45 &mgr;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.
The sieve is removed from the machine and dried in an oven (90° C., 15 min.) and the amount of residue determined.
grit
(
%
)
=
residue
wt
of
zeolite
(
dry
basis
)
General Description of the Invention
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.
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).
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.
The modified aluminosilicate according to the present invention
Appel Peter Willem
Arts Theodorus Johannes Cornelius
Lanceley Carolyn Angela
Osinga Theo Jan
Crosfield Limited
Kopec Mark
Mruk Brian P.
Pillsbury & Winthrop LLP
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