CA1204362A - Zeolite containing detergent compositions and process for preparing same - Google Patents

Abstract

ZEOLITE-CONTAINING
DETERGENT COMPOSITIONS AND
PROCESS FOR PREPARING SAME

ABSTRACT OF DISCLOSURE

Spray-dried detergent compositions prepared by spray-drying aqueous slurries comprising high concentrations of alkali metal silicates in com-bination with aluminosilicate particles which have been coated with from 100 ppm to 2000 ppm of a cationic surfactant contain fewer large aggregates which can deposit on washed fabrics as floc than is the case when the aluminosilicate is not so coated. The improvement is believed to result from an inhibition of the bridging of aluminosilicate particles by silicic acid.

S P E C I F I C A T I O N

Description

1;;~0~3~Z

BACRGROUND OF THE INvENTION

This invention relates in seneral to granular detergent compositions which comprise as essential ingredients an alkali metal silicate, a water-insoluble aluminosilicate and a cationic surfactant.
More particularly it relates to spray-dried detergent compositions containing the aforesaid essential ingredients wherein the aluminosilicate particles are coated with the cationic surfactant in an amount of at least 50 ppm (wt.) at least prior to being subjected to the elevated temperatures and C02-containing environment of the spray dryer, and pre-ferably prior to being brought into contact with an agueous solution of the sodium silicate.
Because of the suspected en~rophication pro-perties attributed to phosphate builders in detergent compositions such as those used for laundering fabrics, it has become conventional in the art to su~stitute for ~ome or all of the phosphate formerly employed, a water-insoluble aluminosilicate which can be either amorphous or crystalline. Another necessary component of such detergents is an alkali-metal silicate, such as sodium silicate. These compounds are found to minimize the corrosion of washing machine surfaces attributed to the other detergent components. In addition it has been proposed that alkali metal silicates are desirable components in spray-dried detergent granules in that they aid in crutcher mix ,~

processing and also aid in maintaininq crisp free-following granules.
It is further known, however, that there are difficulties attendant the use of both alumino-silicates and alkali metal silicates in the same detergent composition. As reported in U.S.P.
4,019,gg9 issued April 26, 1977 to T. H. Ohren et al the~e two constituents have a pronounced tendency to aggregate through bridging of the aluminosilicate particles. In aqueous slurry a chemical reaction takes place which can the theorized as involving ~Si-0~ and/or ~SiO
ionized groups of the aluminosilicate and the alkali metal silicate which can condense to form Si-0-Si linkages and result in the aggregatio~-by bridging.
The aggregates then fail to disperse in-the washing medium hnd deposit on the fabric as a white floc which i8 particularly evident OA dark fabrics.
It has been proposed to avoid the deposition problem by limiting the amount of sodium silicate to less tban about 3S by weight based on the overall weight of the detergent compositions con-taining from 5 to 95 weight per cent aluminosilicate.
This solution is disclosed in U.S.P. 3,985,669 $ssued October 12, 1976 to Rrummel et al. The sodium silicate is employed in the form of a solid particle. ~ third essential ingredient is a water-soluble surface-active agent selected from the group ~20436;i~

consisting of anionic, nonionic, ampholytic and zwitterionic surfactants. It would be desirable, however, to be able to utilize greater concentrations cf alkali metal ~ilicates and~or aqueous solutions o~ alkali metal silicates in preparing detergent compositions.
It iQ therefore the general object of the present invention to provide a detergent composition suitable for spray-drying which contains an aqueous solution of alkali metal silicate in conjunction with an aluminosilicate builder, and which is highly dispers-ible in water even after spray-drying so that floc deposition on fabrics is ameliorated.

SUMMA~Y OF THE INVENTION
.
A spray-dried detergenS composition comprising an alkali metal silicate and an aluminosilicate ion-exchanger prepared by spray drying a precursor com-position containing aqueous alkali metal silicate solution and a cationic surfactant-coated alumino-~ilicate. The cationic surfactant is found to inhibit the tendency of the alkali metal silicate or derivatives thereof formed during spray drying to react with the aluminosilicate particle and create non-dispersable floc aggregates.

~204362 THE PRESEN~ INVENTION
.
The aluminosilicate components uæed in the present invention are any of ~ynthetic or naturally occurring zeolites heretofore proposed for u~e in detergent compositions ~uch as (1) crystalline aluminosili~ate zeolites having the general formula Mx[~AIO2)x(SiO2)y]Z H20 wherein x and y are integers, preferably having a value of at least 6; the molar ratio of x to y is in the range of 0.1 to 1.1; and z is an integer from about 8 to 264, preferably a value such that in the spray-dried detergent product containing s~me, the zeolite contains from about 10 to 30 weight-4 adsorbed water, and M is preferably sodium but can also be potassium, ammonium or substituted ammonium;
or (2) amorphous hydrated aluminosilicate material of the empirical formula M (ZAl2 Y Si2) wherein M is sodium, potassium, ammonium or sub-stituted ammonium, z is from about 0.5 to 2, y is 1 and said material has a magnesium ion exchange capacity of at least about 50 milligrams of CaC03 hardness per gram of ankydrous aluminosilicate; or ~3) mixtures thereof. Mixture of zeolite A and zeolite X wherein either zeolite constitutes at least 30 weight per cent of the overall zeolite mixture and the other zeolite constitutes a com-plementary amount, are especially preferred as the aluminosilicate constituent.

~2043~;2 The c~tionic surfactant is preferably any of the quaternary ~mmonium compounds having the formula l~'R2R3R4 N] Y
wherein At lea t one, but not more than two, of the R- groups is an organic radical containing a group selected from C~ - C22 aliphatic radical, or an alkyl phenyl or ~lkylbenzyl radical having 10 to 16 carbon atoms in the alkyl chain, the remaining group or groups being selected from Cl-C4 alkyl, C~-C4 hydroxy alkyl, and cyclic structures in which the nitrogen atom forms par~ of the ring, Y con-stituting an anionic radical selected ~rom the group consisting of hydroxide, halide, sulfate, methylsulfate, ethylsulfate and phosphate ions.
The alkali metal silicates employed in pre paring the present detergent compositions are preferably sodium silicates with about 1.0 to 4.0 moles of SiO2 per mole of Na2o. Equivalent potassium and lithium silicates are also useful. The alkali metal ~ilicates are preferably employed in the form of concentrated aqueous solutions containing from 20 to 60~ solids, but hydrated and anhydrous silicate powders can be imparted to the overall detergent composition along with an appropriate amount of water if desired.
It is an important ~spect of this invention that the aluminosilicate constituent be coated with the cationic surfactant, or a portion thereof, before there is contact of the aluminosilicate with the lZ0~362 alkali metal silicate under conditions which permit significant reaction between the~e two materials.
Advantageously, and preferably, the aluminosilicate is c~ated with from about 100 ppm to,about 2000 ~pm of the cationic surfactant before any contact with ~n agueous sodium silicate solution i allowed, i.e. the aluminosilicate-cationic surfactant com-posite i8 imparted to the crutcher as an already prepared ma~erial. In all events the aluminosilicate must contain the cationic ~urfactant coating before the overall detergent composition is subjected o spray-drying.

While ~ot wishing to be bound ~y any particular theory, it is belie~ed that ~he principal cause of bridging of the aluminosilicate particles to form undesirable aggregates is a condensation reaction between silicic acid an/or terminal silanol groups on polymerized silicic ~pecies and -Si-OH groups of the aluminosilicate. While relati~ely ~mall amounts of 5ilicic acid are present in the alkali metal silicate solution employed, there is apparently enough to cause appreciable floc formation even at ambient room temperatures during prolonged periods.
In the spray-dryer, however, the detergent feed containing relatively large amounts of water is contacted at elevated temper~tures, i.e., 500F to about 900F, by a rather high concentration of carbon dioxide. This permits the formation of H2C03 which then can react with the alkali metal silicate to produ~e ~ilicic acid in accordance with the following 7 ~0436Z

equation:
(OH~30 ~a + H2C03 - 2 Si(OH)4 ~ Na2C03 The ~ilicic acid in ~urn bonds to ~lumino6ilicate (zeolite) ~urfaces by the following equat~on:

~gOL~ ;URFACE.~EOLITE SURF'ACE

0~ Na ~ N~,~ N~a~ Nn~
OH ~ OH ~ ~ ~10 ~ OH ~2H2 Na~ O~ N~ N ~ I Na~
L I f 1 1 ~
~i Al 1 Si Al /1\/1\/1\ 11\ /1\ /1\
~EOL2TE l;U~FACE ZEOI.ITE SURFACE

of course mon~eric 8iliCic acit is not the only active species, and polymerized silica can also be considered to ~e a reactive bonding agent.
The cationic surfactant coating on the aluminosilica~e $nterferes with th~ or ~imilar ~onding reaction~
without inhibiting appreciably the ion exchange activity of the aluminosilicate when the detergent is adted to the washing metium.
The method of coating the aluminosilicate with the ~urfactant i8 not B crltical factor. Ortinarily the alumin-o~ilicate i6 s$mply slurried or otherwlse washed with a olution of the ~urfactant in ~ suitable solvent such as water or a mixture of water and polar organic solvent ~uch as i~opropanol.

-8- i~04~

There i8 a con~iderable attraction between the cationic surfactant and the ~i~ic aluminosilicate, and accordingly other types of surfactants, builders and other traditional detergent ingred$ents can be included in the present composition~ ~ithout 1088 of the benefits obtained using the three essential inRredients alone.
The compositions, properties and preparation of other organic surfactants are well represented in the patent literature and a detailed review of such readily available naterial will not be undertaken here. We hereinafter disclose examples of certain classes of and individual surfactants that can be used in the detergents of our invention. It is not intended that the ~cope of our invention be l~mited to these specific materials, but that equivalent materials also be includet.
Anionic surfactants are partlcularly important in the deter~ent compositions of our invention. Such anionic materials include, among others, alkali metal soaps of fatty acids, alkali metal salts of alkyl sulfuric acit reaction products, sodium alkyl glyceryl ether sulfonates, succinamates and anionic phosphates, one of the most commonly uset anionic surfactants is the sodium salt of linear alkyl benzene sulfonate (LAS) wherein the alkyl group contains more than lO carbon atoms. LAS forms at least a part of many of the surfactant ~ystems used in our tetergent compounds ant may be the only surfactant u~ed.
Nonionic surfactants are also useful and include, ~mong others, polyethylene ox~de condensate of alkyl -9- ~20~3f;2 phenol~, condensation products of aliphatic alcohols wieh ethylene oxide, nonyl phenol-ethylene oxide con-densates, amine oxides and posphine oxides.
Ampholytic surfactants such as ~hë aliphatic deriva-tives of heterocyclic secondary and tertiary 2mine~ and zev~tterion$c surfactants such as derivatives of al~phatic qusternary ammonium compounds are also useful.
Although sufficient ~luminosilicate-cationic surfac-tant composite builder ant alkali metal silicate can be used to accommodate any laundering environment it may be desired to lnclude an auxiliary builder in the detergent compositions of our ~nven~ion. Such auxiliary builders $nclude salts of phosphates, pryophosphates, orthophos-phates, polyphosphates, phosphonates, carbonates, ant poly-hydrsxysulfonates, organic sequestering agents such as polyacetates, earboxylates, polyaminocarboxylates and polyhydroxysulfonates are of use in our tetergent compo-sitions. Specific exE~ples of useful materials inclute sodium ant potassiu~ salts of tripolyphosphate, pyrophos-phate, hexametaphosphate, ethylenediaaminotetraacetic acit, nitrilotriacetic acid, citric acitS citric acid isomers ant others.
The present detergents can also include numerous additional detergent ingredients. Antiretiposition agents ~s~ch as sodium carboxymethyl cellulose prevent certain types of soils from retipositioning on clean fabric. Minor detergent ingredients such as enzymes, optical brighteners and bleaches are included to remove stains and/or improve the appearance of the fabric. Other minor detergent -~o- ~0436Z

ingredients ~uch a~ perfume~, anti-caking agents, dyes, colored specks and fabric ~ofteners are added to lmprove the properties or appearance of the detergent or the fabric. Since detergent actives are effective ~t low concentrations, it i5 ~mportant the bulking agents be added to the formulation so tha~ measurement of the appro-priate dose i8 facilitated. We have found bulking agents such as sodium sulfates, sodium chloride and other neutral alkali metal ~alt~ to be effective.
The detergent oompositions of this invention thus comprise, prior to spray-drying:
(a) 0 to 30Z by weight of one or more organic ~ur-factants;
(b) 10 to 90Z by weight of a builder system consist-ing of (1) 1 to 9o parts by weight of an alumino-~ilieate having as a coating on the particles thereof, at least 50 ppm by weight of a cationic surfactan~, said aluminosilicate being (i) a crystalline aluminosilicate zeolite having the general formula M,~[ (A102)X (Sio2)y]z H20 wherein x and y are integers, the molar ratio of x to y being ~n the range of 0.1 to 1.1, and ~ is an integer from about 8 to 264; or (ii) an amorphous hydrated aluminosilicate having the empirical formula Mz(ZAl2 Ysi2) 2043~2 wherein M is sodlum, potassium, ammonium or ~ubstituted ammonium, z is from about 0.5 to 2, y i5 1, ~aid material hav~ng a magnesium ion-exchange capacity of~~t least about 50 m$11igrams of CaC03 hardne~ per gram of anhydrous aluminosilicate; or ~iii) mixtures of (i) snd ~ii); and

(2) 4 to 35 parts by weight of a water soluble alkali metal ~ilicate ha~ing a molar composition equivalent to 1.0 to 4.0 ~oles of SiO2 per mole of Na2O, said alkali metal silicate being in the form of an aqueous solution having a solids content of from 20 to 60 weight per cent.
From presently available test data i~ appears that signi-ficant improvement in the ~nhibiting aggregation tue to alumino-silicate bridging i obtained when as little as about 100 ppm (wt.) of the cationic surfactant is coatet on the alumino-silicate particles. It ~ppear~ that ~ith coatings constituting more than about 2000 ppm (wt), no further improvement is obtained, and in f~ct some decrease in effectiveness results compared w$th the effectiveness of lesser amounts. Accordingly it ~s preferred that the aluminosilicate composites contain a coating of from about 100 ppm to 2000 ppm by weight based on the anhydrous weight of the aluminosilicate.
~xAmple 1 In order to demonstrate the effectiveness of cationic ~urfactant-treated zeolite particles in promoting the dis-persability of a spray-dried detergent containing high levels of Eodium silicate and zeolite particles, two spray-dried detergents were prepared in which the only significant dif-12 ~Z043fiz ference was in the zeolite constituent. In Gne sample(~) the zeolite particles were coated with about 500 ppm of a c~tionic quaternary ammonium (alkyltrimethylammonium chloride in which the prLmary alkyl group contains ~rom 14 to 18 carbon ~toms). In ~ample 3, the zeolite was untreated.
The composition contained:
Weight-~
_ .. .. , , . _ component Sample A SamDle B
-- .. _ ...
4A zeolite (anhydrous) 24.8 24.3 Sodium silicate SiO2fNa2O ~ 2.4(wt.) 9.2 9.4 CO3(as Na2CO3~ 33.4 33.2 Volatiles tLoss on heating to 100C.) 8.8 11.7 ~ Coated with 500 ppm cationic surfactant (anhydrous basis Both samples were subjected to a di~solution screen analysis procedure which utilized a tergotometer, a R.O.
Tap Testing Sieve ~haker, a series of seven U.S. standard sieves (Nos. 30, 40, 50, 70, 100, 200 and 325, plus top and bottom), drying oven, a 10~ diameter ~uchner funnel, a 3~" diameter Buchner funnel, a 2 liter vacuum flask, a 4 liter Erlemeyer flask, Watman No. 1 filter paper and an aspirator. The analysis procedure was as follows:
: : (a) The clean sieve series plus sieve bottom and

3~ ~uchner funnel twith ~ilter paper) were dried in a 100C

oven, cooled to room temperature, and weighed.
(b) One liter of a ~olution of hardness water (150 ppm, Ca++/Mg++ ~ 3/2) was heated to 50C in the tergotometer.
(c) Twenty-five grams of the detergent sample to be te~ted was added to the hardness water in the tergotometer ~20436Z

and the content~ agit~ted for 10 minutes at 100 RPM.
(d) A ~ieve tower~ i8 prepared from the ~ieve series ~nd ~et into the 10~ diameter Buchner ~unnel, whi~ is incerted into the four liter Erlemeyer fl~sk.
(e~ The ~ontents of the tergotometer were ~mptied into the sieve tower. Par~icles clinging to ~he ~ergoto~eter tub were rinsed out with distilled water and added t~ the same tower.
(f) When ~t was ob~erved that water was no longer dripping from the sie~e tower, the bottom was placed on the tower and the entire apparatus placed in a 100C drying oven for twenty-two hours.
(g) The collected liquid fraction was filtered with the aid of vacuum using ~he weighed 3~N Buchner funnel and Whatman No. 1 filter paper.
(h) The 3~ Buchner funnel with filtered contents was placed in a 100C drying oven for twenty-two hours.
(i) After drying the sieve top was placed on the sieve tower ~nd along with the Buchner funnel was allowed to cool to room temperature.
(j) The sieve tower was placed in the R.O. Tap Testing Sieve Shaker for three minutes.
(k) Each sieve plus bottom and Buchner funnel was weighed and any increase in weight noted.
(1) The total solids recovered plus the percentage of olids on each sieve were recorded. The percent~ge of solids collected on the sieve bottom and the filter were combined to represent the ~ine fraction.

~;~04;~;Z

Screen analysi~ of the skarting samples showed that the median particle ~ize o~ Sample A was about 360 micrometers, ~nd ~or Sample B the median pnrticle size was about 345 ~icrometers. The re~ults of the dissolution screen analysis procedure ~howed th~t detergent Sample A (containing the ~urfactan$ coated zeolite) dispersed to the degree that the median par~icle size was less than 44 micrometers, whereas the compari~on Sample B Icontaining untreated zeolite particles)~
th~ dispersion was ~uch that the ~edi~n particle size was about 120 micrometers.

Claims (6)

WHAT IS CLAIMED IS:

1. A spray-dried detergent composition prepared by spray-drying a detergent composition comprising:
(a) 0 to 30% by weight of one or more organic surfactants;
(b) 10 to 90% by weight of a builder system consisting of (1) 1 to 90 parts by weight of an aluminosilicate having as a coating on the particles thereof, at least 50 ppm by weight of a cationic surfactant, said aluminosilicate being (i) a crystalline aluminosilicate zeolite having the general formula Mx[(AlO2)x (SiO2)y]z H2O
wherein x and y are integers, the molar ratio of x to y being in the range of 0.1 to 1.1, and z is an integer from about 8 to 264; or (ii) an amorphous hydrated alumino-silicate having the empirical formula Mz(zAlO2' ySiO2) wherein M is sodium, potassium, ammonium or substituted ammonium, z is from about 0.5 to 2, y is 1, said material having a magnesium ion-exchange capacity of at least about 50 milligrams of CaCO3 hardness per gram of anhydrous aluminosilicate; or (iii) mixtures of (i) and (ii); and (2) 4 to 35 parts by weight of a water soluble alkali metal silicate having a molar composition equivalent to 1.0 to 4.0 moles of SiO2 per mole of Na2O, said alkali metal sili-cate being in the form of an aqueous solution having a solids content of from 20 to 60 weight per cent.

2. Detergent composition according to claim 1 wherein the cationic surfactant coated on the aluminosilicate parti-cles is in an amount of from 100 to 2000 ppm by weight.

3. Detergent composition according to claim 2 wherein the aluminosilicate is a crystalline zeolitic molecular sieve.

4. Detergent composition according to claim 3 wherein the cationic surfactant is a quaternary ammonium compound having the general formula [R, R2 R3 R4 N]+ Y -wherein at least one, but not more than two, of the R-groups is an organic radical containing a group selected from C8-C22 aliphatic radical, or an alkyl phenyl or alkylbenzyl radical having 10 to 16 carbon atoms in the alkyl chain, the remaining group or groups being selected from C1-C4 alkyl, C2-C4 hydroxy alkyl, and cyclic structures in which the nitrogen atom forms part of the ring, Y constituting an anionic radical selected from the group consisting of hydroxide, halide, sulfate, methylsulfate, ethylsulfate and phosphate ions.

5. Detergent composition according to claim 4 wherein the quaternary ammonium cationic surfactant is an alkyltrimethylammonium chloride wherein the alkyl group contains from 14 to 18 carbon atoms.

6. Detergent composition according to claim 4 wherein the aluminosilicate is zeolite A and the alkali metal silicate is sodium silicate.