Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
85~
This invention relates to bleaching compositions. More particular-
ly, it relates to such compositlons based on sodium perborate tetrahydrate,
which, due to a content oE molecular sieve 7,eolite, are non-caking on
storage.
Bleaching compositions based on sodium perborate are known and it
is realized that the effectiveness of such bleaches depends on the release
from them of active oxygen. The decomposition of the sodium perborate and
the release of the oxygen may be accelerated by heating or through the
employment of activators, many of which have been described in the prior
art. Otherwise, the release of active oxygen from sodium perborate solutions
is often too slow to be successful in bleaching operations. However, during
storage slow decomposition of the perbora~e may occur, whether or not
activators are used, with attendant release of moisture and the released
moisture may act to form hydrates or co-hydrates with other inorganic salts
in the bleaching composition, such as sodium silicate, sodium carbonate and
sodium sulfate. The net result of such a recrystallization is often the
production of a severly caked product. Such a product is not susceptible to
post-treatment, after caking, to make it free flowing. Therefore, the
caking problem confronted in the manufacture and sale of perborate-based
bleaches when sodium perborate tetrahydrate was employed in them was a
significant
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one and such products had to be very carefully packaged, stored
and formulated to avoid caking and accompanying loss of value.
A simple and effective solution to this problem is the subject
of this patent application.
In its broadest sense, the present invention is a non-
caking bleaching composition which comprises by weight, from 15
to 50% of sodium perborate tetrahydrate, from 25 to 75% of water
soluble inorganic salt and from 5 to 30% of a dry molecular
sieve zeolite having the capacity to be hydrated or further
hydrated to the extent of at least 10% of its weight, the pro-
portion of molecular sieve zeolite being at least 1/4 that of the
sodium perborate tetrahydrate in the composition. Preferably,
the composition will be free of phosphates and phosphorus com-
pounds and will contain primarily sodium perborate tetrahydrate,
sodium silicate, sodium carbonate, sodium sulfate and type hA
molecular sieve zeolite in substantially anhydrous form, with
each of the components being present in certain given ranges of
proportions. Also preferably, most of the composition will be
in spray dried bead or globular form, with the sodium perborate
tetrahydrate being present as a separate finely divided powder.
All or part of the proportion of molecular sieve zeolite present
may also be in such powder form and part may be in the spray
dried beads.
According to the present invention, there is provided
a non-caking bleaching composition comprising by weight, from
15% to 50% of sodium perborate tetrahydrate; from 25% to 75% of
a water soluble inorganic salt selected from the group consisting
of sulfates, carbonates, silicates, phosphates, and mixtures
thereof, said inorganic salt being a #odium or potasslum salt;
from 5% to 30% of a water insoluble molecular sleve zeollte
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having a particle diameter of from 0.5 to 12 microns and having
the capacity to be further hydrated to the extent of at least
10% of its weight, said zeolite containing less than 10% water
and having a univalent cation selected from the group consisting
of sodium, potassium, lithium, ammonium and hydrogen, the pro-
portion of molecular sieve zeolite being at least 1/4 that of
the sodium perborate tetrahydrate in the composition; and below
5~ of free moisture.
The sodium perborate utilized in the present
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invention is in the form of the tetrahydrate. Flowever, accompanying the
required amount of tetrahydrate it~ the present compositions may be other
forms of the perborate and other percompounds, e.g., sodium carbonate
peroxide, sodium percarbonate, with the perborate normally being the major
percompound bleaching constituent. Also, during storage, the tetrahydrate
may sometimes lose water, even when not decomposing, to form the lower
hydrate, sodium perborate monohydrate, and to form the anhydrous borates.
However, in the most highly preferred embodiments of the present invention
the sodium perborate will be in the form of the tetrahydrate.
With the sodium perborate tetrahydrate there will be present
inorganic salt(s), such as water soluble salts of silicic acids, carbonic
acid, sulfuric acid and polyphosphoric acids. Preferably such salts will
be alkali metal salts and of the alkali metal salts, although both sodium
and potassium salts may be utilized, the sodium salts are preferred. The ~ -
most preferred salts are sodium silicate and sodium sulfate, although sodium
carbonate is also a very useful component. The salts act as carriers for
the percompound and they may also function to adjust the pH of the bleach
water. The silicates and phosphates exert water softening effects,
minimizing the production of insoluble and gelatinous soaps and other
calcium and magnesium compounds which may be undesirable in bleaching
operations. Such sequestrants are also especially useful to prevent iron
staining of any of the materiaIs being treated. Of course, iron staining
may not be a problem in the presence of an active bleach but sometimes it
can be.
For most desirable effects in ~he present compositions as a
builder and a sequestrant for magnesium ions the sodium silicate should be
Na20:SiO2 ratiol ~n the range of 1:2 to 1:2:8. Preferably this range is
from 1:2.2 to 1:2.6, e.g., 1:2.~. Although polyphosphates, such as
pentasodium tripolyphosphate and tetrasodium pyrophosphate, may be employed
(and also the corresponding potasslum salts) they will often have to be
omitted to comply with laws forbidding their use ln detergent and bleach
78556
compositions. Additionally, when they are allowed to be employed in
perborate bleach formulations the caking problem is diminished, due to the
greater ability of the phosphates to absor~ moisture without the formation
of cement-like crystals or co-crystals with the other salts present.
The molecular sieve zeolites utilized in making the invented
bleaching compositions are water insoluble, crystalline aluminum silicate
zeolites of natural or synthetic origin which are characterized by having
a network of uniformly sized pores of very small size, e.g., about 3 to 10
Angstroms, which size is uniquely determined by the unit structure of the
zeolite crystal. Zeolites containing two or more networks of differently
sized pores can also be employed. Amorphous forms of zeolites may also be
useful but the crystalline forms, with pores of regular sizes, are better.
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~C3785S6
The molecular sieve zeolite employed is preerably
also a univalent cation-exchanging zeolite, i.e., it should be
an aluminosilicate containing a univalent cation such as
sodi~m, potassium or lithium, when practicable, or o~ ammonium
or hydrogen. Preferably~ the univalent cation associated with
the zeolite molecular sieve is an alkali metal, especially
sodium or potassium, most preferably sodium.
Crystalline types of zeolites utilizable as
molecular sieves in the invention, at least in part, include
zeolites of the following crys~al structure groups: A, X, Y,
L, mordenite and erionite. Mixtures of such molecular sieve
zeolites can also be useful, especially when type A zeolite,
e.g., type 4A, is present. These preferred crystalline types
of zeolites are well known in the art and are mo~e particularly
described in the ~ext, ~eolite Molecular Sieves, by Donald W.
Breck, published in 1974 by John Wiley ~ Sons. Typical com-
mercially available zeolites of the aforementioned structural
types are listed in Table 9.6 at pages 747-749 of the Breck
text.
Preferably the molecular sieve zeolite used in the
invention is a synthetic molecular sieve zeolite. It is
also preferable that it be of type A crystalline structure,
more particularly described at page 133 of the aforementioned
text. Especially good results are generally obtained in
accordance with the invention when a type 4A molecular sieve
855t;
zeolite is employed wherein the univalent cation of the zeolite is so~ium
and the pore size of the zeolite ls about 4 Angstroms. The especlall~J
preferred zeolite molecular sleves are described in U.S. patent 2,882,243,
which refers to them as Zeolite A.
Molecular sieve zeolites can be prepared in either a dehydrated or
calcined form, the latter form containing from less than about 1.5% to about
3% of moisture, or in a hydrated or water loaded form which contains
additional adsorbDd water in an amount up to about 20 to 30% of the zeolite
total weight, depending on the type of zeolite used. Preferably, the
anhydrous or partially hydrated zeolite molecular sieves are employed in the
compositions of this invention and it is especially important that they be
able to sorb at least 10% of their weight in moisture, which can be incor-
porated into the crystalline structure of the zeolite. Most preferably, the
anhydrous or substantially anhydrous form of the zeolite will be utilized,
normally having a moisture content of less than 5%, preferably less than 3%
and most preferably about 2% or even less. The manufacture of such crystals
is well known in the art. For example, in the preparation of zeolite A,
referred to above, the partially hydrated or hydrated zeolite crystals that
are formed in the crystallization medium (such as hydrous amorphous sodium
aluminosilicate gel) are subjected to high temperature dehydration (calcined
to 3% or less water content), which is normally practiced in preparing such
crystals for use as catalysts, e.g., cracking catalysts. However, in some
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7~S5~
cases the high temperature dehydratlon may be suspended befor~ dehydration ls
complete or the temperature to which the hydrated molecular sieve zeolite is
raised for dehydration may be lower, thereby resulting in the production of
a partially hydrated form of the zeolite which is of a desired moisture
content, e.g., 8%, still capable of sorbing at least 10% (anhydrous basis) of
moisture.
Usually the molecular sieve zeolite should be in finely divided
condition such as crystals (amorphous or poorly crystalline particles may
also find some use) having mean particle diameters in the range of about 0.5
to about 12 microns, preferably 5 to 9 microns and especially about 5.9 to
8.3 microns, e.g., 6.4 to 8.3 microns.
Moisture is present in the described bleaching compositions as
water of crystallization (bound moisture) or as "free moisture", that which
is not chemically bound or in the form of a s,able hydrate, but which may
be` physically held by the bleach composition ingredients. The product can
tolerate a small amount of free moisture but an excess of free moisture will
cause poor flow properties and can lead to caking. In the present composi-
tions, so as to promote the stability of the perborate, it is desirable for
the free or very loosely bound moisture content to be kept as low as possible.
In some cases this may be up to 10% but normally it will be below 5%,
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8~5~i
desirably below 3% and most desirably it will be 2% or ]ess, ideally 0%.
Although with no moisture present it ls virtually impossible fo~ the product
to cake due to hydration and the formation of crystals including water of
hydration, still, with decomposition of the perborate during storage water
is released and the hydratable salts present can be hydrated, and being
hydrated, can form strong bonds between crystals, thereby causing the un-
desirable cementing and caking effect.
In addition to the mentioned components of the product, up to 25%,
preferably up to 15% and more preferably up to 10% of various adjuvants may
also be present for their various effects. Thus, there may be utilized
activators for the percompounds to assist them in releasing active oxygen in
the liquid bleaching medium, normally an aqueous medium. Such activators
include those of both the triazine and acyl types, such as 2-[bis(2- hydroxy-
ethyl)-amino]-4,6-dichloro-s-triazine (BHADT), 2,4-dimethoxy-6-chloro-s-
triazine (DCT), diacetyl dimethyl glyoxime (DDG) and tetraacetyl glycoluril
(TAG).
Synthetic organic detergents may be present and these may be of the
anionic or nonionic types. Although amopholytic and cationic detergents may
sometimes be useful they are not usually employed in the present bleaching
compositions. Also, the anionic synthetic organic detergents, while they are
excellent surface active and detersive materials, can sometimes be at least
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71~556
partially inactivated by the large proportion of bleach present and ~here-
fore may be intentionally avoided. The nonionic detergents appear to be the
most stable in the present bleaches. The nonionic detergents will normally
be lower alkylene oxide condensation products, such as polyethylene oxides,
which may sometimes have polypropylene oxide present but only to such an
extent that the product is still water soluble. Preferred examples of such
materials are the higher fatty alcohol-polyethylene oxide condensates wherein
the higher fatty alcohol is of 10 to 18 carbon atoms, preferably 12 to 15
carbon atoms and the ethylene oxide portion thereof is a chain of 6 to 30
ethylene oxide units, preferably 7 to 15 ethylene oxide units and more
preferably about 10 to 15 ethylene oxide units. Also useful are similar
ethylene oxide condensates of phenols, such as nonyl phenol or isooctyl phenol
but these are not preferred. When the anionic detergents are employed they
will normally have from 8 to 26, preferably from 12 to 22 carbon atoms per
molecule and usually will include an alkyl or aliphat~c chain containing
about 8 to 18 carbon atoms, preferably from 10 to 16 carbon atoms in a
straight chain alkyl group. The most preferred of such detergents are the
alkali metal higher alkylbenzene sulfonates, such as the sodium and
potassium salts, in which the higher alkyl groups are of 10 to 18 carbon
atoms, preferably 12 to 14 carbon atoms and preferably also are
_ g _
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linear. Other such anionic detergents include the alpha-
olefin sulfonates, paraffi.n sulfonates, ethoxylated alcohol
sulfa~es, alkyl sulfates and sulfated higher alkyl phenyl
polyoxyethylene ethanols, all preferably as alkali metal
salts, such as the sodium salts. A list of such detergents
is found in United States patent 3,637,339. Included within
the group of anionic detergents are the higher fatty acid
soaps, the sodium salts of fatty acids of 12 to 18 carbon
atoms.
Among the other adjuvants that may be present
in the bleaching compositions, the most useful are fluorescent
brighteners, colorants and perfumes and in some cases, flow
improving agents, such as clays talthough the molecular sieve
zeolite may often sufficiently improve flow so as to obviate the
employment o any clay). The fluorescent brighteners include
the various cotton brighteners, polyamide brighteners and poly-
ester brighteners, which may be reaction products of cyanuric
chloride and the disodium salt of diaminostilbene disulfonic
acid, benzidine sulfone disulfonic acids, aminocoumarins,
diphenyl pyrazoline derivatives or naphthotriazolylstilbenes,
such as for example, those sold under the names of Calcofluor~
Tinopals RBS and 5BM and Phorwite BHC. Such materials are
described in the article Optical Brighteners and Their Evalua-
tion by Per S. Stensby, a reprint of articles published by
Soap and Chemical Specialties in April, May, July, August and
September, 1967, especially at pages 3-5 thereof.
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The proportions of the various components of the present
bleach are important to its desirable functioning and to obtaining a pro-
duct that will not cake on storage, even when subjected to higher than normal
temperatures. The content of sodium perborate tetrahydrate for desirable
bleaching effects is from about 15 to about 50%, preferably 15 to 40% and
more preferably 30 to 40%, e.g., 32%. Inorganic salt(s) content is from
about 25 to 75%, preferably ~o to 70% and more preferably 50 to 60%, e.g.,
56%. When sodium sulfate and sodium silicate are the only inorganic salts
present the proportions thereof will usually be 30 to 60% of sodium sulfate
10 and 5 to 20% of sodium silicate, e.g., 40% and 15%, respectively and when
sodium sulfate, sodium silicate and sodium carbonate are present the pro-
portions will be about 30 to 50% of sodium sulfate, 5 to 15% of sodium sili-
cate and 5 to 15% of sodium carbonate, preferably, 35 to 40% of sodium sul-
fate, 7 to 12% of sodium silicate and 7 to 12% of sodium carbonate. When
other inorganic salts are present with the sodium sulfate and sodium silicate
(and preferably also with the sodium carbonate), such as pentasodium tripoly-
phosphate, tetrasodium pyrophosphate, sodium bicarbonate and borax, the pro-
portions of such materials or mixtures thereof will usually be from about 5
to 35%, preferably 10 to 25%, and will usually be at the expense of the sodium
sulfate. When sodium chloride is employed as a filler it may replace up to
50% of the sodium sulfate content. The percentages of other materials option-
ally present will also usually replace part of the sulfate.
When activator(s) for the perborate are employed the proportions
thereof will normally be from 10% to 50% of the perborate content, e.g., about
25% thereof. Of course, mixed activators may be utilized and the percentage
given refers to the total amount of activators present. Similarly, mixtures
of the various other types of constituents of the present compositions may
also be present, e.g., mixtures of silicates of different Na20:SiO2 ratios.
The proportion of detergent component utilized, if it is present at all, will
30 generally be from 0.5 to 5%, preferably trom 1 to 3% and it will be employcd
primarily for its surface tension lowering effects. Colorants are normally
present in very small quantities, if at all, usually from 0,01 to 1% and often
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8S56
from 0.02 to 0.1~. The quantity of perfume utilized is variable but general-
ly will be from 0.05 to 1~, preferably from 0.l to 0.3%. Pluorescent
brightener content may be from 0.01 to 2% and is usually from 0.5 to 1.5%.
When it is employed, the percentage of clay (calcined aluminum silicate) flow
improving agent is generally from 0.5 to 5% and preferably is from 0.5 to 2%.
The proportions of the various more significant components of the
present compositions will normally be in the range of about 0.1 to 0.5 : 1 :
0.1 to 0.5 : 0.1 to 0.5 : 0.5 to 2 : for molecular sieve zeolite : sodium
perborate tetrahydrate : sodium silicate : sodium carbonate : sodium sulfate,
preferably 0.2 to 0.4 : 1 : 0.2 to 0.4 : 0.2 to 0.4 : 0.8 to 1.5. Of course,
such proportions are within the percentage ranges previously given. The
moisture content will generally be in a range from about 0,05 to about 0.3 :
1, with respect to the molecular sieve zeolite present, often about 0.08 to
0.2 : 1. With respect to the ratios given, when the sodium carbonate is
omitted from the formula the remaining ratios are still valid.
The various bleaching compositions may be made by admixing powdered
compounds but it is preferred to spray dry, spray cool, drum dry, co-size-
reduce or otherwise produce the major proportion of the composition, including
the inorganic salts and most adjuvants except those which are unstable to such
treatment, less the sodium perborate tetrahydrate and also less all or a part
of the molecular sieve zeolite, and then mix with the major proportion of the
product components the perborate and any remaining zeolite. Preferably,
the major proportion of the product is made by spray drying and the particles
thereby produced, preferably in globular or bead form, are classified or
sieved so that over 95% thereof passes through a No. 8 U. S. Standard Sieve
Series Sieve and less than 10%, preferably less than 5% and most preferably
0%, passes through a No. 140 sieve. More preferably the particle size range
is between No. 10 and No. 100 sieves. The perborate and any other particulate
materials to be post-added to the spray dried product, except post-added
molecular sieve zeolite, will normally pass through a No. 100 sieve and will
fail to pass a No. 400 sieve, preferably passing through a No. 1~0 sieve and
resting on a No. 325 sieve. The zeolite particle sizes have already been
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7~35S6
given and it is evident that they are much finer than the other powdered con-
stituents of the product. Part of th~ zeolite content may be spray dried
with the major proportion, largely an inorganic salt proportion, of the pro-
duct or it may all be post-added. It is sometimes preferred to spray dry
about half to 9/10, more preferably about 3/5 to 4/5 of the zeolite and to
post-add the remaining portion. This provides for the portion of the zeolite
in the spray dried or otherwise globular shaped particles of inorganic salt
plus adjuvants to be less apt to deposit on the materials being bleached and
at the same time permits the post-added zeolite to be intimately associated
with the perborate tetrahydrate to prevent caking of the product by water re-
leased from it. It also helps to counteract the possible unstabilizing
effects of ambient moisture on the perborate. However, normally all the
molecular sieve zeolite will be post-added. The post-added molecular sieve
zeolite may be previously blended with the perborate to be post-added, may be
admixed with the spray dried or otherwise produced major component beads at
the same time as the perborate or may be admixed with the previously admixed
perborate-major component mixture. The spray drying is normally effected by
utilizing drying air at about 250C. in a countercurrent (or concurrent~ spray
drying tower and the sieved or classified particles of the largely inorganic
spray dried product, often while still warm, are blended with the perborate
tetrahydrate, which is at room temperature. It has been found by thermo-
gravimetric analysis that sodium perborate tetrahydrate in the presen~ formula-
tions starts to decompose at temperatures as low as 40C. and therefore it
will usually be desirable to cool the spray dried product to a temperature of
30C. or less before mixing the perborate with it. However, if the described
proportion of molecular sieve zeolite is premixed with the perborate even
mixing at initial spray dried product temperatures as high as 40C. or 45C.
will not cause objectionable caking or tackiness in the product and this is
also the case if the molecular sieve zeolite is admixed with the perborate-
spray dried components mixture within a short time, e.g., 30 seconds to three
minutes a~ter the first mixing is begun and while it is still in progress.
Although all of the molecular sieve zeolite is preferably post-addod and has
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the advantage of being in~imately associated with the percompound so ~hat it
can sorb water therefrom as soon as it is released, thereby preventing ~he
caking, it may sometimes be desirable to have part of the molecular sieve zeo-
lite content spray dried with the rest of the composition because it has been
observed that when it is in the spray dried beads it is less liable to cause
any undesirable deposition on materials being bleached. Such deposition is
not usually of much importance with respect to white or light colored articles
but may be objectionable when darker materials are being treated because the
deposition of the very finely divided particles of the molecular sieve zeolite
thereon, which may occur especially if bleaching is effected in an automatic
washing machine with a draining and rinsing cycle in which water is drawn
through the materials being treated, can cause a dulling of the colors there-
of. Although the presence of the molecular sieve zeolite in either the spray
dried or post-added portion of the present products is permissible, within
the guidelines given above, it is important ~hat there be enough zeolite pre-
sent to be able to counteract any undesirable affects due to release of mois-
ture by the percompound during storage or at other times when it may be pre-
maturely decomposing to release moisture. Thus, the proportion of molecular
sieve zeolite employed should preferably be at least 1/4 that of the sodium
perborate tetrahydrate although lesser proportions will be somewhat useful,
too. Preferably, the molecular sieve zeolite content will be as high as half
the sodium perborate tetrahydrate content and in some cases may be even
greater. Lesser amounts than that required to produce a 0.25 zeolite: perbor-
ate ratio can sometimes result in some caking or poor flow characteristics
developing in the product.
Although it is preferred that the base proportion of the composi-
tion be spray dried and the percompound and some of the zeolite be post-
added it is contemplated that other materials may be post-added too, when
desirable, especially if they are unstable to heat. Thus, nonionic detergent
if solid, may be blended in powder form with the globular particles and ie
in liquid or waxy form, may be sprayed as small droplets or in atomized form
onto tumbling composition particles to distribute it well throughout them.
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Also, perfumes and ~low promoting agents may be sp~ayed onto or blended with
the moving composition particles. When ~nixing or formulating methods are em-
ployed which do not cause the perborate or other materials to become unstable
such materials may be blended with the inorganic salts and other components
initially, rather than being post-added. Generally, however, the preferred
methods described above will be employed for the manufacture of commercial pro-
ducts. In such products it is noted that llttle separation, if any, occurs
on storage, probably due to the very small particle size of the molecular
sieve zeolite and the initial filling of interstices between the spray dried
globules with the fairly large proportion of sodium perborate tetrahydrate
employed. The presence of the hydratable inorganic salts in globular form
limits the contact areas of such particles with each other, so that even if
moisture is released by the perborate tetrahydrate or otherwise gains access
to them, there is a lower probability of adhesion or cohesion between particles
to cause caking. The presence of molecular sieve zeolite with the perborate
or in both the spray dried beads and the post-added material additionally helps
to remove any objectionable moisture and aids in preventing caking. Thus,
storage conditions of the present products are not as critical as those for
products of similar composition but not treated with the molecular sieve zeo-
lite and not having its dehydrating and other functional advantages.
Bleaching of the compositions of this invention may be carried
out at various pH's and concentrations but normally the pH will be in the
range of 8 to 12, preferably ~.5 to 10.5 and most preferably it will usually
be about 9 to 10.5. The concentration of the bleaching composition in the
aqueous medium, such as water, will generally be from 0.01 to 5% and prefer-
ably will be from 0.05 to 1~. The bleaching medium will usually be at about
room temperature, normally from 15C. to 30 C., e. g., 20 to 25C. but may
be in the range of 5C. to 90C. Usually the ratio of laundry to bleaching
solution will be from 0.03 to 1, preferably 0.04 to 0.5. While bleaching may
be effected in any suitable vessel, for convenience it is preferred to employ
the tub of an automatic washing machine.
Although the present bleaches are what may be classified as safe
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bleaches, capable of being used with most materials, Eabrics and dyes, care
should still be taken in the selection of the materials to be bleached.
When the bleaches are added to wash waters containing detergent compositions
the washing times need not be changed from ordinary wash cycle times, which
are usually froM 3 to 45 minutes, preferably being from 5 to 20 minutes in
the United States and from 20 to 40 minutes according to European practice.
Similar or corresponding times may also be employed with respect to the use
of the bleaching compositions alone or the corresponding application times
normally employed for bleaches, e.g. 5 minutes to three hours, may be used.
The present bleaches are useful in removing a wide variety of stains from
fabrics, including coffee, tea, wine and dye stains, as well as in helping
to remove ordinary soils and stains, such as those from dirt, carbon, clays,
foods and body wastes. Such desirable results are obtained without harming
the fabrics being treated and without serious adverse effects on dyed fab-
rics, such as blue-dyed polyester-cotton blends, which are often used as -
test fabrics to determine the safeness of bleaches.
The oxygen releasing percompound also possesses desirable anti-
microbial properties and such properties appear to be aided by the presences
of the molecular sieve zeolite and any surface active agents or organic
detergents also in the bleaching medium. The surface active agent helps to
wet the various surfaces to be treated wi~h the perborate and the molecular
sieve zeolite furnishes nuclei for perborate decomposition in aqueous media
Iwhile the product is in powder form it helps to insulate and stabilize the
bleaching co.npound mixture against decomposition) and also adsorbs or entraps
in its crystalline or amorphous matrix viral and bacterial materials, assist-
ing in the antimicrobial effects of the oxygen-releasing perborate, which
may release oxygen at such nuclei. Of course, the molecular sieve zeolite
prevents lumping and caking of the composition and thereby assists in main-
taining it free flowing and in separate particles which are more readily
dispersed and dissolved when added to an aqueous bleaching mcdium and thereby
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1~8SS~
the danger o~ locali2ed overconcentrations and overbleachings is obvia~ed.
Thus, there is signiicant coaction betw~en the va~ious components o~ the
present bleaching compositions and between them and the su~ace active or
syn~hetic organic detergent components when such are present in these composi-
tions, when the present bleaches are admixed wlth detergent compositions or
when they are added to wash waters which lnclude such compositions.
The various desirable effects described are obtained by means of a
bleaching composition which is free flowing, stable on storage and non-caking
and acceptable bleaching effects and combination washing-bleaching effects
are obtainable without the need to raise the aqueous medium employed to its
boiling point, as is sometimes considered necessary when employing sodium
perborate as a bleach. Furthermore, any fugitive dyes which may be incom-
pletely bleached by the perborate tend to be sorbed by the ultrafine zeolite
molecular sieve particles and thereby do not selectively deposit on other
fabrics being treated, which might otherwise cause an objectionable change in
coloring of such fabrics.
The following examples are given to illustrate the invention but
should not be considered as limiting it. Unless otherwise stated, all parts
in the examples and the specification are by weight and all temperatures are
in C
E MPLE 1
COMPONENTS PERCENT
Sodium perborate tetrahydrate 31.7
Sodium carbonate g
Sodium silicate (Na20:SiO2 = 1:2.35) 9
Calcined aluminum silicate clay
Fluorescent brighteners (mixture of Tinopal 5BM 0.5
Conc.~Geigy] and Stilbene Brighteners)
Sodium sulfate 37.6
Perfume 0.2
Type 4A anhydrous (2% moisture content) 9
molecular sieve zeolite
Moisture 2
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~V~8S56
The above bleaching composition, particularly guitable for the bleach-
ing of permanent press fabrics, such as those based on cotton-polyester mix-
tures and also useful for the bleaching of Dacron*-based products, is made by
spray drying in a countercurrent spray tower, using drying air at about 250C.,
a crutcher mix ~70% solids content) comprising water, sodium silicate solu-
tion, light soda ash, anhydrous sodium sulfate and the mixture of fluorescent
brighteners. The spray dried product obtained, sieved to comprise beads
between 10 and 100 mesh, has a moisture content of about 2%. It is then mixed
in a tumbling drum with sodium perborate, the flow promoting clay is also
admixed and the perfume is sprayed onto the surfaces of the tumbling particles.
The sodium perborate and the clay particles are in finely divided powdered
form, with particle sizes in the range of 140 to 325 mesh. The clay particles
may sometimes be smaller than indicated without any adverse effect on the
properties of the product.
Next, the molecular sieve zeolite, with particle sizes in the 6.4 to
8.3 microns diameter range, is added to the tumbling mass and mixing is con-
tinued for about three minutes, after which time the product is homogeneous
and may be packed for shipment. The entire mixing operation is conducted at
about room temperature, 20 to 25C., but the initial spray dried beads may be
of temperatures higher than room temperature and sometimes such temperatures
are up to 45C. However, in the most preferred processes of this example the
spray dried beads are first cooled to a temperature no higher than 30C. be-
fore mixing them with the sodium perborate tetrahydrate.
The product made is oven tested against a control product made in
exactly the same manner without the post-addition of the molecular sieve zeo-
lite. Both products are stored in covered glass jars in a temperature-
controlled oven at 38C. ~ 0.5C. for 22 hours. After such time the control
product is caked and the experimental product is free flowing. This test
comparison is verified by long term storage (3 to 6 months) under conditions
wherein the product is subjected to heating and in some cases, to relatively
high relative humidities. In such instances the desired improved result is
also obtained for the "experimental" product vs. the control.
*Trade mark - 18 -
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..
~7~S5~
In variations of the above formula, the previously dry sillca~e,
carbonate, sulfate and fluorescent brightener components, as inely divided
powders in the 140 mesh to 325 mesh range, have the perfume sprayed onto the
tumbling surfaces thereof in the manner previously described and are then
admixed with a previously mixed combination of the sodium perborate tetra-
hydrate and the molecular sieve zeolite. The same improved stability on stor-
age results, with the product being of lesser tendency to cake, compared to a
control from which the molecular sieve zeolite is omitted. This is also the
case when the various solid components of the product are co-size-reduced but
it is considered that increased stability and better non-caking properties are
obtained when the molecular sieve zeolite is post-added to the other co-size-
reduced solid components after the perfume has been incorporated in them.
In further modifications of the formula given above the proportions
of the various components are changed, so as to be +10, ~20%, +30% and ~50%,
while stil] being within the ranges of percentages and proportions given in
the specification. Additionally, activators for the perborate are employed,
either B~lADT, DCT, DDG or TAG or various mixtures thereof, to the extent of
25% of the content of perborate tetrahydrate ~replacing equal quantities of
sodium sulfate filler). In all such cases good bleaching, free flowing, non-
caking products result. ~hen, in all such experiments, half of the sodium
sulfate content is replaced by pentasodium tripolyphosphate, tetrasodium
- pyrophosphate, sodium bicarbonate, borax or mixtures of equal parts of any
combination thereof, the product resulting is superior in non-caking tenden-
cies under normal and even under elevated temperature storage conditions.
When only the sodium perborate tetrahydrate and other molecular sieve
zeolite are employed, omitting the other inorganic salts ~usually hydratable),
useful bleaching is obtained and the product is less apt to cake on storage
than is the perborate tetrahydrate alone or with only clay to sorb excess
moisture.
All of the compositions described in this cxample are satisEactory
bleaches and antibacterial compositions when employed alone or in conjunction
with a detergent composition in a combination washing-bleaching treatment.
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~L~78S5~
Such bleachings are effected by employing the bleaching compositions describ-
ed at concentrations of 0.1%, 0.3%, 0.5% and 0.8% in the bleaching of perman-
ent press fabrics ~35% cotton, 65% polyester~ in water of 150 parts per
million hardness, as calcium carbonate, (3:2 Ca:Mg ratio~ as CaC03) at tem-
peratures from 25C. to 80C. Treatment ~imes, which range from ten minutes
to two hours, e.g., 15, 30, 60 and 90 minutes, depending on the material being
bleached and the extent of bleaching necessary, are coordinated with the
temperature of bleaching too, usually with the longer times being employed at
the lower temperatures. Safe and effective bleachings of various laundry
stains, including dyes, fruit stains, clay and organic stains are obtained
and whiter fabrics resul~, Such is also the case when there is mixed with the
bleaching medium a washing concentration, e.g., 0.15%, of heavy duty laundry
detergent, such as one comprising 10% of sodium linear dodecylbenzene sulfon-
ate, 2% of Neodol 45-11 (nonionic de~ergent), 1% of sodium higher fatty acid
soap (4:1 hydrogenated tallow : hydrogenated coconut oil~, 35% pentasodium
tripolyphosphate, 15% sodium sulfate, 5% moisture and 2% adjuvants. In such
tests the ratio of fabrics to be bleached : bleach composition will usually be
in the range of 0.04 to 0.5, e.g., 0.2.
EXAMPLE 2
A composition of formula like that of the formula of Example 1 is
made with the exceptions that half of the molecular sieve zeolite is present
in (spray dried with) the spray dried composition and ~hat 1% of clay and 1%
of the sodium sulfate are replaced by Neodol* 45-11 (nonionic higher fatty
alcohol polyethoxyethanol) which is sprayed onto the tumbling spray dried
product before admixing therewith of the sodium perborate tetrahydrate and the
balance of the molecular sieve zeolite.
The product resulting is tested in the same manner as previously
described and is found to be improved over a control product containing no
zeolite, with respect to non-caking and free flowing characteristics. ~lso,
when tested by the methods previously described it is a useful bleaching
composition, especially at the higher temperatures mentioned.
*Trade mark
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` ~78556
Similar mo~i~ications o~ the composition are made w~erein 1/~ and 3/~
of the molecular sieve zeolite are incorporated in the crutcher mix. In all
such cases ~when the ~olecular sieve zeolite is spray dried) less muting of
the colors o-f dark colored materials and fabrics results.
The described experiments are repeated with the other variations o-f
the formula of Example 1, with acceptable bleaching and flow characteristics
resulting in the products made.
EXAMPLE 3
The various compositions of Examples 1 and 2 are modified by utiliz-
ing a type 4A molecular sieve which is 10% hydrated. At moisture contents of
1% and 2% in the product the partially hydrated molecular sieve is effective
in preventing caking due to decomposition of small proportions of the sodium
perborate tetrahydrate present. However, because the capacity of the mole-
cular sieve zeolite for hydration is diminished ~compared to an anhydrous
molecular sieve zeolite) the compositions are less able to tolerate moisture
and are less likely to be protected against caking over prolonged periods or
when the product is subject to elevated temperatures and/or humid conditions.
Resistance to caking is about comparable to that of those products wherein
half of the anhydrous type 4A molecular sieve zeolite is present in the spray
dried composition (wherein it is partially hydrated due to being mixed with
water in the crutcher).
Of course, the products of this example are useful perborate bleaches
when employed in the manners described in the previous examples.
EXAMPLE 4
The compositions of Examples 1-3 are modified by replacing the type
4A molecular sieve zeolite with other type A molecular sieve zeolites and with
those of types X, Y and L. The molecular sieve zeolites utilized are essen-
tially anhydrous, containing less than 2% of moisture. The products made are
of improved non-caking and free flowing properties, compared to control pro-
ducts wherein the molecular size zeolites are not present. However, the type
4A molecular sieve zeolite of Examples 1-3 is preferred for best anti-caking
activity and water softening properties.
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~~"` ~ ` ~L137~3S 5~;
The invention has ~een descr-i~ed w~th respect to various illus-
trations and examples thereof but ~s not to be li~lted to these because it is
evident that one of skill in the art will be able to utilize substitutes and
equivalents without departing from the spir~t of the invention.
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