Note: Descriptions are shown in the official language in which they were submitted.
3q~c
c~
AGGLOMERATED PEROXYACID BLEACH GRANULE AND
PROCESS FOR MAKING SAME
,
Charles E. Kellner
Steven R. Alexander
BACKGROUND OF THE INVENTION
The present invention is related to a peroxyacid bleach
granule and a process for converting a water-wet mixture o~
materials compr;sing a peroxyacid bleach and exothermic control
materials to a stabilized dry granule.
The prior art contains references which disclose compositions
containing mixtures of peroxyacids with exothermic control ma-
terials. The use of an agglomeration process to make peroxyacid
bleaching granules is suggested generically in U.S. Pat. No.
4,170,453, Kitko, issued Oct. 9, 1979. This reference, however,
does not address the favorable or unfavorable aspects, or the
specifics, of an agglomeration process.
Preparing low density peroxyacid bleach prills in a spray
tower is disclosed in commonly assigned U.S. Pat. No. 4,497,757,
Beimesch/Hortel, issued Feb. 5, 1985. Other background references are IJ.S.
Pat. Nos. 3,703,772, McHugh et al., issued Nov. 28, 1972; and commonly
assigned 4,091,544, Hutchins, issued P~Iay 30, 1978. Such prior art processes
require several extra steps to obtain higher density peroxyacid bleach granules. SUMMARY OF THE INVENTION
The present invention relates to a dry, peroxyacid bleach
granule composition and a novel process for making it comprising:
spraying wet peroxyacid bleach onto dry granular components of the
dry bleach composition in a suitable mixer under controlled
conditions.
DETATLED DESCRIPTTON OF THE INVENTION
The present invention provides a dry agglomerated bleach
granule which comprises a complex mixture of peroxyacid bleach and
a stabilizing amount of a solid peroxyacid bleach exotherm control
~,"
- 2 -
agent. The present invention also provides a process for making
the agglomerated bleach granule.
The term "agglomeration" as used herein means forming a
particulate by coating, sticking and mixing including forming a
dough-like intermediate and combinations thereof.
The granule of the present invention has a complex crystal-
line containing structure as oi~posed to the spherical particles or
flakes as disclosed in the prior art, e.g., U.S. Pat. Nos.:
4,091,544 and 4,497,757, both supra.
The process is an energy saver over the prior art, ensures
better bleach granule uniformity, removes water from a wet per-
oxyacid bleach intermediate without exotherming and with less
degradation.
The process of the present invention comprises the following
steps:
A. Forming a pumpable, preferably sprayable, water-wet
slurry of:
(1) from about 26% to about 55% water;
(2) from about 20X to about 45% of the peroxyacid
bleach; and
(3) at least about 1/3 of a stabilizing amount of a
peroxyacid exotherm control agenti
8. Forming wet bleach granules from the wet slurry of
Step A via pumping or spraying it onto a dry feed
stream of particulate solids containing at least a
balance of said e~othermic control agent in a mechanical
mixer; the wet bleach granules of this step having a
free moisture content of from about 10% to ab~ut 20%;
and
C. Drying the wet bleach granules of Step B at a controlled
temperature to a final free moisture content of less
than about 0.5%.
The granule has a free moisture content of less than about
0.5% for stability and flowability. The density of the granules
of this invention are at least about 0.5 gm/cc. The preferred
density is from about 0.6 to about 0.7 gm/cc. Prior art granules
prepared by prilling have densities of 0.35 gm/cc to 0.45 gm/cc,
wPll below 0.5 gm/cc. The preferred free moisture content of the
granule of this invention is from about 0.1% to about 0.~%.
The preferred level of water in Step A is -from about 30% to
about 40%. The preferred moisture content in Step B is from about
12% to about 18%. The preferred final free moisture content of
the granules in Step C is from about 0.1% to about 0.3%.
In a continuous process, the average mixing time of Step B is
brief, pre~erably from about 0.2 seconds to about 5 seconds.
; The drying time of Step C in a fluid bed dryer is pref2rabl~
from about 10 minutes to about 60 minutes. The preferred drying
inlet air temperature of Step C is from about 35~C to about 100C,
keeping the temperature of the wet granules below about 60C.
The term "controlled temperature" in Step C means a tem-
perature below a bleach destabilizing temperature.
The preferred temperature of the slurry of Step A is from
about 30C to a maximum of about 40C. The more preferred process
temperatures for Step A are from about 34C to about 38C, and for
Step C is from about 38C to about 82C. The drying is preferably
conducted in a fluid bed dryer.
The term "pumpable" as used herein means that the slurry can
be introduced into a mechanical mixer containing dry particulate
components as a stream or a spray.
The level of peroxyacid bleach in the dry bleach granule is
preferably from about 10% to about 35%, more preferably from about
20% to about 30%, by ~eight of the granule.
The PeroxYacid Bleach
~ The peroxyacid can be any suitable peroxyacid. Examples of
- suitable organic peroxyacids are disclosed in U.S. Pat. No.4J374~03S~ F. P. Bossu, issued Feb. 15, 1983; and U.S. Pat. No.
4,770,666, A. D. Clauss, issued Sept. 13, 1988.
The peroxyacid bleach is used at a level which provides an
amount of available oxygen (AvO) of from about 0.1% to about 10%,
preferably from about 0.5% to about 5%, and most preferably from
about 1% to about 4%. A preferred bleach granule comprises 1% to
3S 50% of an exotherm control agent (e.g., boric acid); 3% to 25% of
a peroxyacid compatible surfactant (e.g., C13LAS); 0.01% to 10% of
one or more chelant stabilizers (e.g., sodium pyrophosphates); and
10% to 50% of a water-soluble processing salt (e.g., Na2S04).
..
- 4 -
A preferred peroxyacid bleach is used at a level which
provides an amount of available oxygen (AvO) of from about 1.2% to
about 5X, preferably from about 2% to about 4%, and most prefer-
ably from about 2.5% to about 3.5%.
A preferred peroxyacid material for use in the present
process is a normally solid peroxyacid compound. A compound is
"normally solid" if it is in dry or solid form at room tempera-
ture. Such peroxyacid compounds are the organic peroxyacids and
water-soluble salts thereof which in aqueous solution yield a
species containing a -0-0- moiety. These materials have the
general formula
o
"
HO - O - C - R - Y
wherein R is an alkylene group containing from 1 to about 20
carbon atoms or a phenylene group and Y is hydrogen, halogen,
alkyl, aryl or any group which provides an anionic moiety in
aqueous solution. Such Y groups can include, for example,
O O O
~ "
- C - OM, - C - O - OM or - S - OM
wherein M is H or a water-soluble, salt-forming cation.
Examples of suitable aromatic peroxyacids and salts thereof
includ~ monoperoxyphthalic acid, diperoxyterephthalic acid,
4-chlorodiperoxyphthalic acid, the monosodium salt of diperoxy-
terephthalic acid, m-ch70roperoxybenzoic acid, p-nitroperoxy-
ben~oic acid, and diperoxyisophthalic acid. The most preferred for
use in the instant process are diperoxydodecanedioic acid, nonyl-
amideperoxysuccinic acid (NA~SA~, and diperazelaic acid.
The PeroxYa~cid Exothermic Control Aqent
Preparing the peroxyacid wet mix of Step A and reducing the
water content of the peroxyacid wet mix in Step B and the drying
of the wet bleach granules of Step C, all require care. It is
desirable to remove virtually all of the water from the wet
granule in the drying Step C so as to improve the available oxygen
stability of the peroxyacid. The mixing temperatures and the mix
compositions of Steps A and B and the air temperature of Step C
must be controlled and must not be allowed to reach a point where
- 5 -
exotherm or substantial degradation accords. Thus, it is neces-
sary that steps be taken to ensure that the mixing and drying
temperatures do not allow the peroxyacid to exothermally decom-
pose. To he'lp control the exotherm problem, an agent is put into
the mixture which releases water at about the exotherm point of
the bleach and thereby contro`lling it. Agents of this type will
be discussed subsequently.
The time of exposure to the drying temperature is variable
depending on the temperature chosen, the materials, the thickness
of the individual particles and the drying technique, but will
generally be from about several minutes to several hours at a
temperature of from about 25C to about 100C, preferably from
about 60C to about 70~C, as long as the temperature of the bleach
granule itself does not exceed about 60aC. Preferably the tem-
perature of the drying bleach granules is kept below about 55C.
Th~ actual unit used for this final drying can be any whichdoes not involve the particles pressing together. The term "~luid
bed dryer," as used herein, includes moving belt dryers (forced
air circulation), and any kind of forced air circulation dryers
such as the Wyssmont Turbodryer supplied by Wyssmont Company of
Ft. Lee, New Jersey, which can be used to dry the wet bleach
granules of the present invention.
It is well documented in the peroxyacid literature that
peroxyacids are susceptible to a number of different stability
problems, as well as being likely to cause some problems. Looking
at the latter ~irst, peroxyacids decompose exothermally and when
the material is in dry granular form the heat ge~erated must be
controlled to make the product safe. The best e~otherm control
agents are those which are capable of liber~ting moisture at a
temperature slightly below the decomposition temperature of the
peroxyacid employed. U.S. ~at. No. 3,770,816, Nielsen, issued
Nov. 6, 1973, discloses a wide variety of hydrated materials which can serve as
suitable exotherm control agents. Lncluded among such materials are
magnesium sulfate .7H20, magnesium formate dihydrate, calcium sulfate
(CaSO4.2H20), calcium lactate hydrate, calcium sodium sulfate
(CaSO4.2Na2SO4.2H20), and hydrated forms of such things as sodium
aluminum sulfate, potassium aluminum sulfate, ammonium aluminum
:, ~
- 6 -
sulfate, and aluminum sulfate. Preferred hydrates are the alkali
metal aluminum sulfates, particularly preferred is potassium
aluminum sulfate. Other exotherm control agents include
"hydrates'' of other suitable salts. The preferred exotherm
control agents are those materials which lose water as the result
of chemical decomposition such as boric acid, malic acid and
maleic acid.
The exotherm control agent is preferably used in a stabil-
izing amount of from about 70% to about 400%, more preferably of
from about 75% to about 200%, and most preferably from about 100%
to about 150%, based on the type and weight of the peroxyacid
compound and the type of control agent used.
Larger amounts of some of these materials are required to
control exotherm than the preferred exotherm control agents.
Other Materials
The other problems faced when peroxyacid compounds are used
fall into the area of maintaining good bleach effectiveness. It
has been recognized that metal ions are capable of serving as
catalyzing agents in the degradation of the peroxyacid compounds.
To overcome this problem, chelating agents can be used in an
amount ranging from about 0.005% to about 1% based on the weight
of the composition to tie up heavy metal ions. U.S. Pat. No.
3,442,937, Sennewald et al., issued May 6, 1969, discloses a
chelating system comprising quinoline or a salt thereof, an alkali
metal polyphosphate and, optionally, a synergistic amount of urea.
U.S. Pat. No. 2,838,459, Sprout, Jr., issued. June 10, 1958,
discloses a variety of polyphosphates as stabilizing agents for
peroxide baths. These materials are useful herein as stabilizing
aids. U.S. Pat. No. 3,192,255, Cann, issued June 29, 1965,
discloses the use of quinaldic acid to stabilize percarboxylic
acids. This material, as well as picolinic acid and ~-hydroxy-
quinoline would also be useful in the compositions of the present
invention. A preferred chelating system for the present invent;on
is a mixture of dipicolinic acid, and an acid polyphosphate,
preferably acid sodium pyrophosphate. The acid polyphosphate can
be a mixture of phosphoric acid and sodium pyrophosphate wherein
the ratio of the former to the latter is from about 0.5:1 to about
2:1 and the ratio of the mixture to dipicolinic acid is from about
0.2:1 to abut 5:1.
- 7 -
Additional ayents which may be used to aid in giving good
bleaching performance include such things as pH adjustment agents,
bleach activatorS and minors such as coloring agents, dyes and
perfumes. Typical pH adjustment agents are used to alter or
maintain aqueous solutions of the instant compositions within the
5 to 10 pH range in which peroxyacid bleaching agents are gen-
erally most useful. Depending upon the nature of other optional
composition ingredients, pH adjustment agents can be either of the
acid or base type. Examples of acidic pH adjustment agents
designed to compensate for the presence of other highly alkaline
materials include normally solid organic and inorganic acids, acid
mixtures and acid salts. Examples of such acidic pH adjustment
agents include citric acid, glycolic acid, tartaric acid, gluconic
acid, glutamic acid, sulfamic acid, sodium bisulfate, potassium
bisulfate, ammonium bisulfate, and mixtures of citric acid and
lauric acid. Citric acid is preferred by virtue of its low
toxicity and hardness sequestering capability.
Optional alkaline pH adjustment agents include the conven-
tional alkaline buffering agents. Examples of such bufferiny
agents include such salts as carbonates, bicarbonates, silicates,
pyrophosphates and mixtures thereof. Sodium bicarbonate and
tetrasodium pyrophosphate are highly preferred.
Optional ingredients, if utilized in combination with the
active peroxyacid/exothermic material system of the instant
invention to form a complete bleaching product, comprise from
about 50rO to about 95% by weight of the total composition.
Conversely, the amount of bleaching system is from about 5% to
about 50% of the composition. Optional in~redients such as the
metal chelating agent is preferably mixed with the peroxyacid and
the exothermic control agent in Step A or Step B, thereby becoming
a part of the dry units formed in the process. Others such as the
pH adjustment agents are added as separate particles in Step B or
admixed with the granules of this invention. Such other ingre-
dients may be coated with, for example, an inert fatty material if
the ingredients are likely to cause degradation of the peroxyacid.
The bleaching compositions as described above can be added to
and made a part of conventional fabric laundering detergent
ccmpositions. Accordingly, optional materials for the instant
~o~Ls~n
- 8 -
bl~aching compositions can include such standard detergent adiu-
vants as surfactants and builders. Optional surfactants are
selected from the group consisting of organic anionic, nonionic,
ampholytic and zwitterionic surfactants and mi~tures thereof.
Optional builder materials include any of the conventional organic
builder salts including carbonates.
Water-soluble salts of the higher fatty acids, i.e., "soaps"
are useful as the anionic surfactant herein.
Another class of anionic surfactants includes water-soluble
salts, particularly the alkali metal, ammonium and alkanolammonium
salts, of organic sulfuric reaction products having in their
molecular structure an alkyl group containing from about 8 to
about 22 carbon atoms and a sulfonic acid or sulfuric acid ester
group. (Included in the term "alkyl" is the alkyl portion of acyl
groups.)
Preferred water-soluble anionic organic surfactants herein
include linear alkyl benzene sulfonates containing from about 11
to 14 carbon atoms in the alkyl group; the tallow range alkyl
sulfates; the coconut range alkyl glyceryl sulfonates; and alkyl
ether sulfates wherein the alkyl mo;ety contains from about 14 to
18 carbon atoms and wherein the average degree of ethoxylation
varies between 1 to 6.
Specific preferred anionic surfactants for use herein
include: sodium linear C1o-C12 alkyl benzene sulfonate; tri-
ethanolamine C1o-C1~ alkyl benzene sulfonate, sodium tallow alkyl
sulfate; sodium coconut alkyl ylyeeryl ether sulfonate; and the
sodiu~ salt of a sulfated condensation product of tallow alcohol
with from about 3 to about 10 moles of ethylene oxide.
It is to be recognized that any of the foregoing anionic
surfactants can be used separately herein or as mixtures.
The instant granular composit;ons can also comprise those
detergency builders commonly taught for use in laundry com-
positio~s. Useful builders herein include any of the conventional
inorganic and organic water-soluble builder salts, as well as
various water-insoluble and so-called "seeded" builders.
Inorganic detergency builders useful herein include, for
example, water-soluble salts of phosphates, pyrophosphates,
orthophosphates, polyphosphates, phosphonates, carbonates, bi-
- 9 -
carbonates, bo~ates and silicates. Examples of these and other phosphorus
b~lilder compounds are disclosed in U.S. Pat. Nos. 3,159,581; 3,213,030;
3,422,021; 3,4~2,137; 3,400,176 and 3,400,148. Sodium tripolyphosphate is an
especially preferred, water-soluble inorganic builder herein.
Non-phosphorous containing sequestrants can also be selected
for use herein as detergency builders. Specific examples of
non-phosphorus, inorganic builder ingredients include water-
soluble inorganic carbonate, bicarbonate, borate and silicate
salts. The alkali metal, e.g., sodium and potassium, carbonates,
*
bicarbonates, borates (Borax) and silicates are particularly
useful herein.
~ater-soluble organic builders are also useful herein.
Highly preferred non-phosphorous builder materials (both
organic and inorganic) herein include sodium carbonate, sodium
bicarbonate, sodium silicate, sodium citrate, sodium oxydisuc-
cinate, sodium mellitate, sodium nitrilotriacetate, and sodium
ethylenediaminetetraacetate, and mixtures thereof.
Another type of detergency builder material useful in the
present compositions and processes comprises a water-soluble
material capable of forming a water-insoluble reaction product
with water hardness cations in combination with a crystallization
seed which is capable of providing growth sites for said reaction
product.
Another type of builder useFul herein includes various
substantially water-insoluble materials which are capable of
reducing the hardness content of laundering liquors, e.g., by
ion-exchange processes.
The complex aluminosilicates, i.e., zeolite-type materials,
are useful presoaking/washing adjuvants herein in that these
materials soften water~ i.e., remove Ca++ hardness. Both the
naturally occurring and synthetic "zeolites", especially zeolite A
and hydrated zeolite A materials, are useful for this builder/-
softener purpose. A description of zeolite materials and a method
of preparation appears in Milton, U.S. Pat. No. 2,882,243, issued
April 14, 1959-
*Trade Mark
.~
- 10 -
The bleach granules of th;s invention can be used with soil
release agents. Any suitable soil release agent can be used
including those disclosed in U.S. Pat. No. 4,770,666, ~E~-
Any dry materials used in Step B as part of the "dry feed,"
including excess exothermic control agent materials, builders,
etc., are referred to herein as "fillers" unless otherwise
specified.
The peroxyacid bleach granules of the present invention can
be admixed with other compatible granular bleach and/or detergent
composition materials. The particle sizes of the bleach con-
taining granules or optional granular material are not critical.
However, commercially acceptable flow properties having certain
granule size limitations are highly preferred. Thus, the granules
of the instant compositions pre~erably range in size from about
100 microns to 3,000 microns, more preferably from about 1~0
microns to 1,300 microns, and most preferably from about 250
microns to about 1,000 microns.
Bleaching compositions of the present invention are utilized
by dissolving them in water in an amount sufficient to provide
from about 1.0 ppm to 100 ppm available oxygen in solution.
Generally, this amounts to from about O.OlYo to 0.2% by weight of
composition in solution. Fabrics to be bleached are then con-
tacted with such aqueous bleaching solutions.
The dry granular peroxyacid bleach composition of the instant
invention and the process for making same are illustrated by the
following examples, but not limited thereto. Percentages and
parts are by weight.
EXAMPLE 1
A dry granular peroxyacid bleach composition is prepared
using thc following:
Wet PeroxYacid Bleach SlurrY Parts
Diperoxydodecanedioic acid (DPDA) 0.93
22.9%; water 46%; boric acid 25.2%;
surfactant paste ~ minors 5.9%
DrY Feed Solids
Anhydrous sodium sulfate 0.35
Recycled dry DPDA fines 2.g5
~d Total 4.23
~.,,~
- 11 2~
The equipment used is a Bepex 8" TC8 Turbulizer mixer and an
Aeromatic batch type, fluid bed dryer Model STREA-l made by
Aeromatic AG, Muttenz.
The wet peroxyacid bleach slurry is prepared by adding the
boric acid and the surfactant paste + minors to the aqueous
solution of diperoxydodecianedioic acid.
Steo B -
The recycled dry feed DPDA fines and sod;um sulfate are
blended in the proportions shown and introduced into the Tur-
bulizer mixer. The dry feed solids temperature is about
18'C. The si~e of the DPOA fines is under 250 microns and
the size of the sulfate is between about 180 microns and 285
microns. The wet slurry (30C) is metered from a tank and
sprayed using an air atomized nozzle onto the dry feed solid
components in the Turbulizer mixer. The exiting material, in
the form of wet granules~ is collected and transferred to the
Aeromatic dryer. The temperature of the wet granules out of
the Turbulizer mixer is about 30DC.
Step C -
The wet granules are therein dried and the dried bleach
granules are cooled down in the dryer.
The final b~each granules are then analyzed for density,
particle size and chemical composition. The speed, blade angle,
and clearance in the Turbulizer mixer are adjusted during the
experiments to optimize granule size. The wet granules are dried
with about 65C air for about 30 minutes and then cooled to about
18C in the dryer.
A description of the dried peroxyacid bleach granules of
Example 1 follows: moisture about 0.2%; density about 0.64 gm/cc;
percent DPDA about 25%; percent boric acid about 27%; and sodium
sulfatP about 46%. About 90% of the granules have a particle s ke
in the range of from about 250 microns to about 1,750 microns; and
; ~ an average particle size of about 500, ~75 microns.
The surfactant paste and minors composition for Example 1 is
as follows:
- 12 -
Inqredient Parts
LAS (Linear alkylbenzene 34.26
sulfonate 28%; sulfate 22%;
water 50%)
Dipicolinic acid (DPA) 0.09
Phosphoric acid (H3P04) 0.2
Trisodium phosphate (TSPP) O.11
Total 34.46
The three minors (DPA, H~IPO4 and TSPP) are prem;xed with the
LAS paste in the proportions shown. The anhydrous sodium sulfate
acts as a filler and also serves as a secondary exothermic control
agent/heat sink.
EXAMPLE 2
The following ingredients are used:
Wet PeroxYacid Bleach Slurry Parts
Diperoxydodecanedioic acid 25.55%; 3.01
water 46.5%; boric acid 19.68%;
surfactant paste + minors 8.27%
DrY Feed Solids
Anhydrous sodium sulfate 1.28
Boric acid powder 0.25
Recycled dry DPDA fines (250 microns) 5.46
Total10.00
The equipment used is a Bepex 8" TC8 Turbulizer Mixer and a
Bepex 1 sq. meter continuous fluid bed dryer. The process and
equipment are similar to those of Example 1, except that a
continuous fluid bed dryer ;s used.
SteD A -
The wet peroxyacid bleach slurry (30C) is prepared by adding
the boric acid and the surfactant paste + minors to the
aqueous solution of diperoxydodecanedioic acid.
Ste~ B -
The wet slurry (30C) is metered from a tank and sprayed
using an air atomized nozzle onto the dry solid components
(ambient temperature) in the Turbulizer mixer.
*Trade lilark
A`~
- 13 -
Step C -
Wet granules from the Turbulizer mixer are fed continuously
to the Bepex fluid bed dryer. The drying air to the first
two zones of the Bepex fluid bed is about 65'C. The
temperature of the drying granules is controlled and kept to
less than about 30C during the drying. A third zone of the
Bepex is supplied with ambient air to cool the dried bleach,
Final dried bleach granules have a moisture of about 0.3%;
a density of about 0.61 gm/cc; DPDA 24%; boric acid about
28%; and sodium sulfate about 42.5%.
The sulfate and boric acid solids of Example 2 are fed
separately using volumetric feeders. The recycled dry bleach
fines, which are produced in the fluid bed dryer (Step C), are
separated from the desired particle size granules and recycled to
the mixer of Step B as dry feed solids. The bleach granules in
the dryer which are below about 250 microns in size are continu-
ously removed from the dryer. The,dry bleach granular particles
over about 1,750 microns in size are screened out and ground up to
; 20 less than about 250 microns and then recycled as dry solid fines
in Step B in the dry feed.
; In the continuous fluid bed drying step of Example 2 orExample 3, the bed is seeded with either recycled peroxyacid
bleach fines or ground bleach granules from a previous run. The
seeding fines, granules and other dry bleach solid components have
; particle sizes preferably below 250 microns. The process is
'~ prefPrably started up using formulatPd proportions of particulate
~ boric acid and sulfate as dry feed and mixing the dry feed with
i the peroxyacid slurry. The first bleach granules are recycled
from the dryer discharge until the target material balance is
reached. Drying air temperature is from about 60C to about 70C.
`~`
'~ .
:'
- 14 -
EXAMPl~ 3
The ingredients used in this example are as follows:
Wet Peroxvacid Bleach Slu~rrv Parts
Diperoxydodecanedioic acid 28.6%; 2.99
water 52.270; boric acid 11%;
surfactant paste + minors 8.2%
Drv Feed Solids
- Anhydrous sodium sulfate 1.52
Boric acid powder 0.61
Recycled dry DPDA fines 6.88
Tota112.00
The equipment used is a Bepex 8" TC8 Turbulizer Mixer and a
Bepex 3 sq~ meter conkinuous fluid bed dryer.
Step A -
The wet peroxyacid bleach slurry is prepared by adding the
boric acid and the surfactant paste + minors to the aqueous
solution of diperoxydodecanedioic acid. The temperature of
the wet slurry is about 30C.
SteD B -
The wet slurry is metered from a tank and sprayed using an
air atomized nozzle onto the dry feed solids in the
Turbu1izer mixer.
The anhydrous sodium sulfate and boric acid solids are
fed separately usin~ volumetric feeders. Recycled dry DPDA
fines which are produced in the fluid bed dryer and separated
from the desired particle size granules are added to the Tur-
bulizer mixer as dry feed solids.
Step C -
Wet granules from the Turbulizer mixer are fed continuously
to the fluid bed dryer. The drying air temperatures are as
follows:
Zone 1 - 70C
Zone 2 - 55C
Zone 3 - 50C
Zone 4 - 10C
Dryer residence time for the drying bleach granules is about
30 minutes. The temperature of the dry bleach granules leaving
~ L5 ~&~13
- 15
the dryer is about 22-C. Their free rnoisture content is about
0.3%. Their density is about 0.63 gm/cc. DPDA content is about
26% Their boric acid content is about 28.4%; and their sodium
sulfate content is about ~2.5%. Their average particle size is
about 500.
The product yield for Example 3 is about 34/0 on a dry basis.
The target peroxyacid concentration in Example 3A is about
10% dry basis (using sulfate as a dry diluent). The yield is
about 81.9% on a dry basis (See Table 1, Example 3A).
The target peroxyacid concentration of Example 3B is 24% on a
dry basis. The peroxyacid slurry moisture content is 32%. The
product yield is 78.95% on a dry basis (See Table 1, Example 3B~.
'
Example 3 Lxample 3A Example 3B
Inqredient Parts Parts Parts
Peroxyacid slurry 2.99 2.99 4.87
(Slurry % moisture) (52.2) (52.2) (32)
Anhydrous sodium sulfate1.52 6.51 3.52
Boric acid 0.61 0.61 1.41
Recycled fines/overs* 6.88 1.89 2.20
Totals12.00 12.00 12.00
.~
Dry yield parts 10.44 10.44 10.44
Yield (dry basis) 34.1% 81.9% 78.95%
% Peroxyacid 24 10 24
* The drying process ~hen in equilibrium typically pro-
duces 1570 to 25% recycle as fines/oversize material.
:
An appropriate recycled DPDA fines composition for Examples
; 1, 2 and 3 is:
Diperoxydodecanedioic acid (DPDA) 24%
Sodium sulfate 43%
Boric acid 26%
LAS paste 5.2%
Minors (includes Na2S04 in paste) 1.3%
Free moisture 0.5%
. ' ,' . ,
.
~s~
- 16 -
Surfactant paste and minors compositions for Examples 2 and 3
are as follows:
Inqredient Parts
LAS (linear alkylbenzene sulfonate 50%; 19.58
sulfate 1%; water 49%)
Dipicolinic acid (DPA) o,09
Phosphoric acid (H3P04) 0.2
Trisodium phosphate (TSPP) o.ll
Total 19.98
The three minors (DPA, H3P04 and TSPP) are premixed with the
LAS paste in the proportions shown. The DPA, TSPP and H3P04 are
added to the formulation as chelatirlg agents to tie up heavy metal
ions. The LAS is used as a processing aid. The temperatures of
the wet granules in Step C for all examples are estimated to be
below about 30C.
When a continuous process of the present invention reaches an
equilibrium, the yield out of the dryer is from about 75% to about
85%. About 5% to about 10% are overs which are ground to DPDA
fines and recycled. About 10% to about 15% of the wet granules
are pulled out of the dryer as fines via an exhaust bag house
collection system.
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