Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1998-08-20
2001-07-10
Kelly, C. H. (Department: 1774)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S322000, C510S377000, C510S507000, C510S532000, C510S466000, C423S328100, C423S700000, C423S709000, C423S712000
Reexamination Certificate
active
06258768
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to crystalline aluminosilicates having the P-structure and to a process for manufacturing the same. These materials are of value as a component in detergent formulations in which they remove calcium and magnesium hardness ions by ion exchange. They also have other properties which provide additional benefits when used in detergent formulations. These aluminosilicates will be referred to as zeolite P in this description.
BACKGROUND OF THE INVENTION
While the utility of zeolite P in detergent formulations has been acknowledged, for example in European Patent Application 0384070 (Unilever), they must be manufactured by a commercially effective process in order to become available on the market place. Thus, while the properties of a material may make it a useful commercial commodity, its manufacture has to be optimised for large scale production.
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
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, caesium 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.
In EP-A-565,364 is described a process for preparing P zeolites in which aluminate and silicate solutions are reacted in presence of P zeolite seeds. During the formation of the crystalline zeolite the reacted medium passes through a gel stage. This process enables the production of high quality detergent zeolites having a Calcium Effective Binding Capacity (CEBC) of above 146 mg/g, with outstanding Calcium Uptake Rate (CUR) and high oil absorption.
In some applications it can be considered to use detergent zeolites with lower detergent characteristics but high oil absorption.
In U.S. Pat. No. 3,112,176 is described a process in which P type zeolites are produced from metakaolin. Having reproduced the examples disclosed in this document, a maximum Calcium Effective Binding Capacity of 90 mg/g has been obtained. Moreover, the kinetics characteristics of these zeolites were found to be very poor with a Calcium Uptake Rate of above 500 seconds.
In U.S. Pat. No. 3,008,803 is described a process in which aluminium hydroxide, silicic acid and water are mixed in a vessel and allowed to react at 100° C. for 48 hours with stirring. The agitation is stopped and the mixture is maintained at 100° C. for an additional 71 hours. A P-type zeolite with a CEBC of 65 mg/g and a CUR of above 500 seconds was obtained.
Now, to be used in detergents applications, a zeolite must exhibit, on top of a good CEBC (at least 100 mg/g), a Calcium Uptake Rate of less than 100 seconds. Therefore the zeolites P disclosed in U.S. Pat. No. 3,112,176 and U.S. Pat. No. 3,008,803 are not suitable for detergent applications.
There is therefore a need for a P-type zeolite with good detergents characteristics (i.e CEBC above 100 mg/g and CUR below 100 seconds) intermediate between those disclosed in U.S. Pat. No. 3,112,176 on the one hand and those disclosed in EP0384070 on the other hand. For the time being, it has not been possible to obtain such a P-type zeolite.
It has now been discovered that it is possible to obtain such an intermediate zeolite.
GENERAL DESCRIPTION OF THE INVENTION
It is a first object of the present invention to provide a P-type zeolite having the oxide formula:
M
2
,O.Al
2
O
3
. (1.8-2.66) SiO
2
.yH
2
O
wherein y is the number of moles of water per mole of Al
2
O
3,
having a Calcium Effective Binding Capacity of between 100 and 145 mg/g, preferably between 110 and 140, most preferably between 110 and 130 mg/g and a Calcium uptake rate of between 12 and 100 seconds, preferably below 50 seconds.
Preferably, the P-type zeolite has an Average Particle Size of between 1 and 10 &mgr;m, more preferably between 3 &mgr;m and 6 &mgr;m.
It is a second object of the present invention to provide a process for manufacturing a P-type zeolite wherein metakaolin is allowed to react with a caustic solution in presence of P-type seeds.
The sources of the seed zeolite P is not critical, although preferably it is added to the reactants as a previously prepared slurry. Alternatively a crystallised slurry from a previous reaction may be used. Additionally the ratio of the P-zeolite seed is not critical and a P-zeolite having a Si:Al ratio above 1.33 can be used.
Preferably a caustic solution is first added into a reactor tank to form a caustic pool, metakaolin being then added to the caustic pool. The caustic pool is heated up to a temperature between 80° C. and 100° C., preferably above 90° C., before adding the metakaolin. More preferably metakaolin is added to the caustic pool in a slurry form.
The metakaolin can have a SiO
2
/Al
2
O
3
molar ratio of 2 to 2.5, typically ratios of 2.15 to 2.2 are easily commercially available.
The zeolite P seeds are added to the caustic pool 5 to 20 minutes after the addition of metakaolin preferably they are added to the caustic pool 10 to 15 minutes after the addition of metakaolin.
It is a third object of the present invention to provide a detergent composition comprising 0.5% to 60% by weight of a surfactant system, 20% to 80% by weight of a detergency builder system, and optionally other conventional components; the detergency builder system comprising, in an amount of 5% to 80% by weight of the detergent composition, an alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not greater than 1.33, the aluminosilicate having a Calcium Effective Binding Capacity of between 100 and 145 mg CaO per g of anhydrous aluminosilicate, preferably between 110 and 140 and a Calcium uptake rate of between 12 and 100 seconds, preferably below 50 seconds.
Standard Procedures
In the characterisation of the zeolite-P materials prepared by the present process the following methods were used.
i. Particle size: The average particle size (microns) was measured by a Malvern Mastersizer (Trade Mark) obtainable from Malvern Instruments, England and expressed as the d
50
, i.e. 50% by weight of the particles have a diameter smaller than the diameter quoted. The definitions d
80
and d
90
may also be used in association with the appropriate figure. Prior to measuring the particle size, the sample is dried as a thin layer (about 1.5 mm) at 110° C. for two hours in a fan oven.
ii. Calcium uptake rate (CUR): The rate of removal of Ca
++
ions from a wash liquor is an important characteristic of a detergency builder. The time, in seconds, is determined for a zeolite, at a concentration of 1.48 gdm
−3
and a temperature of 25° C., to reduce the calcium ion concentration in a 0.01M sodium chloride solution from an initial value of 2×10
−3
M to 10
−5
M. The zeolite was first equilibrated to constant weight over saturated sodium chloride solution and the water content measured.
iii. Calcium effective binding capacity (CEBC): 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 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 0.01M NaCl solution (50 cm
3
) and 0.05M CaCl
2
(3.923 cm
3
), therefore producing a solution of total volume 54.923 c
Garrett Dawn L.
Imperial Chemical Industries plc
Kelly C. H.
Pillsbury & Winthrop LLP
LandOfFree
Zeolite P aluminosilicates and their manufacture and use in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Zeolite P aluminosilicates and their manufacture and use in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Zeolite P aluminosilicates and their manufacture and use in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459834