Note: Descriptions are shown in the official language in which they were submitted.
WO 94/19447 2 ~. ~ ~. 4'~ ~ PCT/US94/00189
SHAPED SOLID COMPRISING OXIDANT BLEACH WITH
ENCAPSULATE SOURCE OF BLEACH
Field of the Invention
The invention relates to shaped solid sources of an
active bleach that can be used in bleaching or cleaning
processes. Active bleach is a common component of many
washing or sanitizing processes including washing of
kitchenware, tableware, flatware, cookware, etc., laundry,
health care appliances, food manufacturing equipment,
pharmaceutical manufacturing equipment, etc.
Background of the Invention
A variety of active bleaching compositions are known
including active halogen bleaches. Active halogen
compositions have been used for many years in a variety of
cleaning or sanitizing methods. Such halogen sources can
come in the form of gases (gaseous C12, Br2, etc.), liquids
(aqueous sodium hypochlorite), or solids, calcium
hypochlorite, chlorinated sodium tripolyphosphate,
chlorinated isocyanuric acid and others. Solids can be
dissolved in water to create a bleach concentrate. Such
materials can be applied to processing by metering a gas or
liquid form of the halogen source into the wash site into an
aqueous stream directed to the wash site. Solid halogen
sources can be used in a variety of washing processes by
adding solids directly to the washing liquor or by metering
an aqueous solution of the chlorine source into the wash
locus.
Solid sources of halogen bleaches have been used in both
aqueous solutions, particulate powders or in
solid tablet or brick form. The solid tablet or brick form
of the solid active bleach source can pose a problem in
control of dispensing. Tablets or bricks of the material are
introduced into aqueous dispensers. The dispensers can be
calibrated to provide various bleach concentrations, often to
provide 1 to l0 grams of halogen per bleach cycle. Within the
dispenser the tablet or tablets are fixed mechanically at a
WO 94/19447 PCT/US94/00189
2
1
fixed distance from an aqueous spray. As the aqueous spray
contacts the surface of the solid bleach material the water
dissolves a portion of the bleach source creating a liquid
concentrate solid which is directed to a wash~bleach cycle.
However, water can be absorbed by the tablet and can soak
through the entire tablet or brick. The water can pass
through this brick and can pass further into adjacent tablets
or bricks. The absorbed water can cause the tablets) or
bricks) to become cracked, split, crumbled or become
"slushy". Such water soaked tablets often become difficult
to dispense with adequate control of bleach concentrate in
the wash liquor. Parts of the tablet can randomly be
released by a disintegrating tablet causing random dispensing
of undesirable, harmful, substantially large concentrations
of halogen into the washing site. In the instance that the
slushy or cracked tablet releases a substantial proportion of
its mass into the dispenser, the dispenser can release 100-
300 grams or more of chlorine source into the washing locus.
Such high concentrations of chlorine can cause metal
corrosion to washer or dispenser, fabric damage, color change
or other harmful results.
The encapsulation of active sources of halogen bleach
with organic and inorganic coatings have been disclosed in
Brubaker, United States Patent No. 4,279,764; Brennen, United
States Patent No. 3,637,509; Idudson, United States Patent
No. 3,650,961; Alterman, United States Patent Nos. 3,983,254
and 3,908,045. Olson, United States Patent No. 4,681,914,
teaches the use of encapsulated sources of active halogen in
cast solid warewashing detergents. In Olson, the
encapsulated halogen source is dispersed in a molten caustic
material that solidifies to form a sodium hydroxide based
warewashing material.
Accordingly, a substantial need exists in processes using '
aqueous sources of halogen to provide a solid halogen source
that can dispense a uniform proportion of the solid mass of '
the halogen source without uncontrolled dispensing problems.
WO 94/19447 - ~ PCT/US94/00189
3
Brief Discussion of the Invention
We have found that control over dispensing solid bleach
tablets can be obtained by manufacturing a tablet from a
source of oxidant halogen bleach including an encapsulated
source of oxidant halogen bleach. Alternatively, the tablet
or solid can comprise both an unencapsulated powder or
granular bleach source and the encapsulated source. The
resulting tablets comprise a continuous solid phase
comprising an unencapsulated source of oxidant bleach with
the encapsulated source of bleach dispersed in the continuous
phase. When used together the unencapsulated bleach can be
used at a concentration of 20-90 wt~ of the tablet and the
encapsulated source of chlorine can be used in the tablet at
a concentration of about 10 to 80 wt~ based on the tablet.
We have found that the encapsulated chlorine source aids in
tablet formation and substantially reduces the harmful
effects of water spray on the solid material. The tablets of
the invention can be placed in the dispenser wherein the
tablets are contacted with a water spray that creates an
aqueous bleach concentrate. The water spray dissolves
controlled amounts of the tablet to introduce into the wash
liquor a consistent well controlled concentration of a
halogen such as chlorine. For the purpose of this
invention the term "brick", "tablet" or "block" connotes a
mass of material greater than about 1 gram having a size and
shape adapted for introduction into a dispenser to be
. contacted with a dissolving/dispensing water spray. The
water spray, dissolving a controlled portion of the tablet
forms an aqueous bleach concentrate that can be directed to a
use locus such as a washing machine. The term solid source
of oxidant bleach or active halogen bleach relates to a
powder, granular, or other pourable solid material that can
release active bleach under washing conditions. Aqueous
bleach concentrates made using the tablets of the invention
can contain up to about 10,000 parts per million of active
oxidant bleach per million parts of aqueous solution. Such
concentrate can be directed into a wash liquor in a wash
WO 94/~ ~''~ ~ PCT/11S94100189
4
machine and can be used at a concentration of a preferred
source of active chlorine in contact with a soiled article in
amounts of about 5 to 500 parts of active chlorine per
million parts of wash liquor. The tablets of the invention
are preferably made by blending a powdered source of chlorine
with an encapsulate source of chlorine in a particulate form. ,
The blended powder is then preferably compressed into tablets
using available technology.
In our experimentation leading to the invention a number
of materials were used to bind powdered or granular sodium
dichloroisocyanurate into useful tablets. Additives such as
Carbowax, fatty acids, inorganic materials, etc. were used as
binders in common compression molded tableting operations.
Overall, we have found that inorganic materials aid in
tableting but failed to reduce the tendency of the chlorine
source to absorb water leading to crumbling and uneven
dispensing. We have found that some organic materials form
adequate tablets with useful dispensing properties but are
unstable in the presence of the highly active chlorine
source. At high temperatures the material can discolor or
smolder at concentrations useful in tableting. Further, we
have found other additive materials that form useful tablets
but introduce substantial hydrophobicity into the tablets
leading to a failure to dispense adequate proportions of
oxidizing bleach. We have found that the encapsulated
oxidizing bleach source provides a number of advantages.
First, the encapsulated bleach source acts as a binder
material permitting the formation of mechanically stable
shaped solids of halogen releasing material. Further, the
coating of the encapsulated oxidizing bleach provides control
over the hydrophobicity of the tablet leading to the
dispensing of controlled amounts of the active bleach. The
encapsulated chlorine source, while acting as a binder and
dispensing control agent, does not substantially dilute the
concentration of chlorine in the tablet. Lastly, the
presence of the encapsulated source provides a stable tablet
which can dispense a controlled even proportion of the solid
WO 94/19447 _ ~ PCT/US94/00189
material into the aqueous concentrate which is then directed
to a cleaning locus for cleaning action on a variety of
articles. The bleach source can be used to clean dishware,
~ tableware, kitchenware, laundry, sheets, towels, food
5 production equipment, pharmaceutical production equipment and
~ any other related surface that requires bleaching, sanitizing
or other action of oxidizing bleaches.
Brief Discussion o~ the Drawings
FIGURE 1 is an illustration of a water spray type
dispenser enclosing a container with three of the preferred
halogen containing circular tablets of the invention.
FIGURE 2 is a graphical representation of a controlled
dispensing of chlorine at a consistent amount of about 5
grams of chlorine per dispensing cycle using the tablets of
the invention.
FIGURE 3 is a graphical representation of an uncontrolled
dispensing of prior art tablets not made in accordance with
the invention resulting in spikes of uncontrolled chlorine
dispensing substantially greater than 5 grams per cycle.
Detailed Description of the Invention
ACTIVE OXIDANT BLEACH
The bricks, tablets or blocks of the invention can
comprise a source of active oxidant bleach such as active
halogen or active oxygen and an encapsulated source of active
halogen oxidant bleach.
The source of active halogen used in the continuous phase
of the solid tablet of the invention and used in the core of
the encapsulated source of halogen can comprise a halogen
releasing substance suitable to liberate active halogen
species such as free elemental halogen (C1, Br, C12, Br2) or -
OC1- or -OBr-, under conditions normally used in detergent
bleaching cleaning processes of a variety of cleaning
targets. Preferably the halogen releasing compound releases
chlorine or bromine species. The most preferred halogen
species is chlorine. Chlorine releasing compounds include
WO 94/19447 ° PCTIUS94/00189
6
potassium dichloroisocyanurate, sodium dichloroisocyanurate,
chlorinated trisodium phosphate, calcium hypochlorite,
lithium hypochlorite, monochloramine, dichloramine,
[(monotrichloro)-tetra(monopotassium dichloro))
pentaisocyanurate, 1,3-dichloro-5,5-dimethylidantonone,
paratoluene sulfodichloro-amide, trichloromelamine, N- '
chloramine, N-chlorosuccinimide, N,N'w
dichloroazodicarbonamide, N-chloroac~etyl-urea, N,N-
dichlorbiurile, chlorinated dicyandiamide, trichlorocyanuric
acid, dichloroglycourea, etc. Chlorinated isocyanurate
materials including dichloroisocyanurate dihydrate, sodium
dichloroisocyanurate, potassium dichloroisocyanurate, etc.
are preferred chlorine sources suitable for the continuous
solid phase and for the core substance of the encapsulated
material. Chlorinated isocyanurates are commercially
available from Monsanto or Olin and other vendors.
ENCAPSULATE
We have found that combining a solid bleach source with
an encapsulated bleach source in a brick, block or tablet
provides substantially controllable dispensing properties in
the solid when contacted with water and provides binder
properties. Encapsulated chlorine sources of the invention
comprise a chlorine source core and at least one
encapsulating layer. The encapsulating layer can comprise an
inorganic material or an organic material. Further, the core
chlorine source can be covered with two, three or more useful
layers. Preferably we have found a two layer coating scheme
wherein the core is coated with a inner inorganic layer and
30~ an outer organic layer comprising a material (detergent,
sequestrant, builder, antiredeposition agent, etc.) useful in
washing liquors. For the purposes of this application the .
term "encapsulating agent", as used herein encompasses solid
soluble inorganic compounds used as inert fillers in
detergent compositions and soluble inorganic builders used in
detergent compositions which contribute to the detergency of
the composition and which do not substantially react with a
WO 94/19447 21514 "~ 5 'PCT~S94/00189
_ 7
halogen bleach. The external organic phase of the
encapsulate can comprise a variety of encapsulating materials
that can be selected from small molecule, monomeric or
polymeric sources.
ORGANIC COATINGS
Small molecule organic compositions that can be used for
the external encapsulate layer comprise a large variety of
water soluble organic compounds.
A preferred class of small molecule organic encapsulate
materials comprise synthetic surfactant compounds. The
synthetic surfactant coating must remain sufficiently solid
at storage or use temperatures encountered by the encapsulate
during storage of the product, for example, temperatures of
about 15 to 50C and also remain stable at temperatures
likely to be encountered during processing of the product.
Synthetic surfactants useful in making the encapsulates of
the invention include anionic, cationic, nonionic and
amphoteric surfactant compositions. Examples of anionic
surfactants useful in the encapsulate compositions of the
invention are the higher alkyl mononuclear aromatic alkali
metal sulfonates such as alkyl benzene sulfonate, xylene
sulfonate, alpha olefin sulfonates, primary and secondary
alkyl sulfates and others. Alkali metal salts of fatty acids
commonly classified as soaps can be used in the definition of
an ionic detergent. Examples of such operable soaps include
sodium and potassium salts of acyclic monocarboxylic acids
having 8 to 12 carbon atoms. A particularly suitable
synthetic surfactant for use in a coating composition is
sodium alkyl sulfonate having from about 6 to 12 carbon
atoms, preferably sodium octyl sulfonate.
Typical nonionic surfactants are commonly materials that
contain polymer ethylene oxide, propylene oxide or heteric or
block copolymers thereof. Such materials can be made as the
condensation products of alkyl phenols having 5-15 carbon
atoms any alkyl group, the condensation product with a long
chain fatty alcohol or acid, etc. These nonionic surfactants
WO 94/19447~'~~'~~~ PC'f/US94/00189
8
are well known in the art and are available to the skilled
artisan. Cationic and amphoteric surfactants are known but
are not preferred for these applications. Suitable builders
that can be used in the compositions of the invention include
weakly acid neutral or alkaline reacting inorganic or organic
compounds especially inorganic or organic complex forming
substances such as the bicarbonatxe~s', carbonates, borates, and
silicates of alkali metal or al)ca~.i earth metal salts. The
alkali metal ortho, meta, pyro~and tripolyphosphates are a
useful filler/sequestrant material. Another class of
suitable builders are the insoluble sodium alumina silicates.
Generally, the shaped solid sources of active bleaching agent
of the invention can also contain other elements which impart
varying degrees of physical or chemical characteristics.
Constituents such as optical binders, deodorizers,
antiredeposition agents, dyes, perfumes, dispersing agents,
etc. can be added to the shaped solids for known properties.
SOLUBLE INORGANIC COATING AGENT
Inorganic materials suitable for the coating of the
encapsulate of the invention include alkali such as sodium
bicarbonate, sodium sesquicarbonate, sodium borate, potassium
bicarbonate, potassium sesquicarbonate, potassium borate,
phosphates such as diammonium phosphate, monocalcium
phosphate, monohydrate, tricalcium phosphate, calcium
pyrophosphate, iron pyrophosphate, magnesium phosphate,
monopotassium orthophosphate , potassium pyrophosphate,
disodium orthophosphate dihydrate, trisodium orthophosphate
decahydrate, tetrasodium pyrophosphate, sodium
tripolyphosphate, a sodium polyphosphate compound, sodium
hexametaphosphate, potassium tripolyphosphate, a potassium
polyphosphate compound, neutral or soluble salts such as
sodium sulfate, sodium chloride silicates, inorganic
sequestering agents and antiredeposition agents and hydrates
thereof. Suitable builder compounds that can be used in the
coatings of the encapsulate include tetrasodium or
tetrapotassium pyrophosphate, pentasodium or pentapotassium
WO 94/19447 - ~ ~ ~ ~ PCT/US94/00189
9
tripolyphosphate, sodium or potassium silicates, hydrated or
anhydrous borax, sodium or potassium sesquicarbonate,
phytates, polyphosphonates and others.
The manufacture of the encapsulated source of oxidizing
bleach can be carried out by first providing an initial
inorganic protective passivation coating of the core material
which can be conveniently applied using fluidized coating
apparatus. In making encapsulated materials, the
particulates are introduced into the fluidizing chamber of a
fluidized bed. The bed of particles to be coated is then
suspended with the fluidizing atmosphere. A nozzle is
typically introduced into or nearby the fluidized bed through
which liquid droplets of coating material are discharged in a
diverging pattern coextensive with the upper surface of the
bed. Coating solution is applied to the bed at a temperature
required for rapid drying of the coating solution on the core
particles. Solvent vapors can be removed from the fluidized
bed with a blower. Once the particles are fully covered with
an initial coating, subsequent coatings can be formed in a
similar fashion using known technology. The encapsulated
oxidizer of the present invention can contain 20 to 90 wt~ of
the active oxidizing bleach core and 10 to 80 wt~ of a
coating. In the instance that dual coating are used, the
encapsulated material can comprise about 20 to 90 wt~ of an
oxidizing bleach core, about 0.5 to 50 wt~ of a first
passivating inorganic coating agent and about 5 to 70 wt~ of
a second synthetic surfactant second coating. More
particularly, the single coated oxidizing bleach comprises 30
to 80 wt~ of bleach core and about 20 to 70 wt~ synthetic
surfactant coating, most particularly about 40 to 55 wt~ of
oxidizing bleach core and 45 to 60 wt~ of the first coating.
A most preferred embodiment of the double coated oxidizing
bleach encapsulate comprises about 30 to 80 wt~ of the bleach
core, about 5 to 50 wt~ of a first inorganic coating agent
and about 5 to 50 wt~ of a second synthetic surfactant
coating. Other materials may be present in the coating layer
such as conventional additives used in bleaching or cleaning
CA 02151475 2005-03-21
laundry, dishware, etc: Typical examples include well known
soil suspending agents, corrosion inhibitors, dyes, perfumes,
fillers, optical brighteners, enzymes, germicides,
antitarnishing agents, and the like.
5
MANUFACTURING PROCESS
The shaped solids of the invention can be made using a
variety of known shaping technologies. The shaped so~.ids can
be made by compression processes, the use of molten binding
10 agents, and others well known to the skilled artisan. The
process for manufacturing the shaped sol-.~d compositions of
the present invention generally comprises two steps. First,
the constituent powders used in the shaped solids are
introduced into a mixing apparatus to form a homogeneous
powder blend. Commonly available mixing apparatus such as
ribbon blenders can be used. The homogeneous powder blend is
then placed in a~commonly available press which can compress
the powders into a shaped tablet, brick or block. Generally
the preblended powder or granulate is placed in a hopper with
feeder systems and metered into a tabletizer. The tablet
size can vary from about 1 gram to 100 grams and greater.
Preferably, the tablet comprises from 500-2000 grams and can
take any convenient shape. One shape readily made by most
compression tabletizers is a disc or cylinder. The cylinder
~ diameter can range from approximately 1/4 inch to 5 inches (6.35 to 127
mm) or greater having a thickness of about 1/4 to about 5.91 inches
(6.35 to 150 mm), preferably about 0.5 inch to 3 inches (12.7 to 76.2
mm) .
Detailed Discussion of the Figures
Figure 1 is a cross section of a portion of the dispenser
used for introducing the active halogen bleach concentrate
made using the shaped solids of the invention. In Figure 1
the dispenser housing 10, a portion of an overall housing for
a dispenser that can be adapted for dispensing one, two or
more encapsulated solid materials can be configured for
dispensing the shaped solids of the invention. An example of
the dispenser shown in the Figure is the Solid System IIIT"
WO 94/19447 ~ ~ ~ PCT/US94/00189
11
dispenser. Such a dispenser is used in laundry dispensing.
In Figure 1 a spray nozzle 11 is shown with a cone-shaped
spray 12 directed from the nozzle 11 onto the surface of the
shaped solids 16 contained within a plastic capsule 17 which
is then attached to the dispenser with a threaded connector
20 and shoulders 21 that cooperate with the housing of the
nozzle 22. In the operation of the dispenser, fresh water is
introduced into the dispenser through conduit 13, the water
is sprayed through the.nozzle 11 onto the shaped solid 16
creating a concentrate. The concentrate then passes down
through the opening of the capsule 20 through the screen 19
to the outlet 15. Any large portions of the shaped solid
that is released can be trapped by the screen 19.
Figure 2 is a graphical representation showing that
dispensing the shaped solids of the invention can achieve a
controllable dispensing rate that can range from about 10 to
about 20 grams of the shaped solid per spray cycle. No
undesirable peaks of large amounts of chlorine bleach is
shown dispensed in the Figure.
In sharp contrast, Figure 3 shows the uncontrolled
dispensing of large spikes of high concentrations of chlorine
bleach using the prior art compressed tablet comprising
chlorinated isocyanurate in the absence of the encapsulate.
The Figure shows small spikes of up to 30 grams of chlorine
bleach per spray cycle but also shows significant spikes of
chlorine bleach reaching levels of about 130 grams per spray
cycle. Such peaks or spikes of chlorine bleach caw do
serious harm to laundry equipment and laundry load.
Examples and Data
A number of examples of the shaped solids that can be
used to dispense active halogen concentrates were made. The
solids were tested to show that they could dispense
controlled even amounts of bleaching concentrate without
dispensing harmful excessive amounts of oxidizing bleach.
Our experiments were done using commonly available sources of
WO 94/19447 ~ ~ ~~ PCT/US94/00189
12
chlorine bleach, however we believe the invention can work
with a variety of powdered sources of halogen bleach. 3~7e
believe that there is a useful interaction between the
powdered bleach material and the encapsulate which produces a
stable tablet, controlled dispensing, and sufficient
hydrophobicity to prevent the disge~nsing water from
destroying the tablet during dispensing. The following
examples contain a best mode.
Example 1
A series of shaped solids in the form of a cylinder
having a 4 inch diameter and an approximately 1 inch height
were made containing about 600 total grams of material. The
tablets contained varying proportion of additive materials.
The ingredients used to make the tablet were added to a
mechanical blender and shaken until uniform. The material
was then introduced into a hand tablet compression device.
The powder was compressed into a tablet at a pressure of
about 11,000 pounds of pressure for a press time of about 30
seconds. The shaped solids produced are shown below in Table
I.
~1~14"~~
WO 94/19447 ' PCT/US94/00189
13
TABLE I
Example 600-Gram, Additives Number of
4-Inch Solid Concentration
Additives
Table ( ~s )
Quantity
1 3 1 2 (Organic Binder)
..
2 3 ,,. , 2 1 (Organic Binder)
3 3 3 2 (Organic Binder)
4 3 1 1 (Organic Binder)
lA 3 1 2 (Organic Binder)
3 2 2 (Organic Binder)
6 3 1 1 (Laurie Acid)
7 3 2 1 (Laurie Acid)
8 3 100 1 (C12-Encapsulate)
9 3 10 1 (Laurie Acid)
3 10 1 (Carbowax~)
11 3 30 1 (C12-Encapsulate)
12 3 25 1 (C1z-Encapsulate)
13 3 20 1 (C12-Encapsulate)
14 3 15 1 (C12-Encapsulate)
Capsule filled with calcium hypochlorite mini-tablets
(Pittabs)
CA 02151475 2004-05-06
WO 94/1944? ~ PCTlUS9:1100189
14
The active halogen source used was a sodium salt dehydrate of
chlorinated isocyanuric acid (CDB-56). The 600 gram, 4 inch (101.6 mm)
solid tablets with various binders and other ingredients were
then tested in an automatic dispensing system. Three tablets
of each kind were stacked in a'plastic disposable bottle or
capsule. The capsule containing the tablets was inverted on
a load cell which continuously monitored its weight. Water
was sprayed upward into the pellet onto the tablet contents
at a duty cycle of 15 seconds spray on; 15 minutes spray off
for a continuing cycle. Eight pounds per square inch water
pressure was used with 125°F water. Examples 1-5 made using
1-3 wt$ of a variety of organic and inorganic binder
additives suffer severely from slushing problems leading to
uncontrolled dispensing. An example of uncontrolled
dispensing is shown in Figure 3 which is a graphical
representation o.f the dispensing experiment performed on the
tablet of Example 3. During dispensing at the 100-105 cycle,
at the 200-225 cycle, at the 300-310 cycle and about at the
380 cycle, large uncontrolled excursions of chlorine
concentration were dispensed substantially greater than 20
grams per dispensing cycle. The maximum amount of chlorine
source dispensed in this test was 134.1? grams of the
chlorine source late in the test. The phenomenon of
"slushing" is indicated by the unusually large spikes or
peaks of uncontrolled chlorine dispensing usually preceded by
cycles of extremely small amounts dispensed. In other words,
we believe the shaped solids soak water from the spray
nozzle, gradually losing its mechanical integrity leading to
initial cracks and finally to crumbling which leads to the
release of substantial proportions of the mass into the
dispenser stream. The phenomenon of "slushing" was also
monitored visually as a slow expansion of the tablet height
and the development of fissures and cracks. Time video tapes
of the tablets during dispensing were also made. These
visual observations were used together with the dispensing
figures in judging how well the different tablets were being
dispensed. The tablets 6 and 7 made using 1-2 wt~ lauric
WO 94/19447 ~ PCT/US94/00189
acid also suffered severe slushing problems. The tablet
shown in Example 10 using 10~ of a polyethylene glycol
(Carbowax 8000) binder system exhibited excellent dispensing
profile, however on thermostability testing, the Carbowax
containing materials decolorized and showed substantial
thermal instability between the chlorine source and Carbowax.
The Examples 11-14 with 15, 20, 25 and 30 wt~ of an
encapsulated chlorine source, respectively, exhibited
excellent dispensing profiles and thermostability. Example 8
made entirely of encapsulated chlorine source displayed
excellent dispensing properties. However, the use of all
encapsulate is expensive and not commercially attractive.
Example 15 using calcium hypochlorite showed excellent
dispensing properties but suffered from the drawback that the
use of this chlorine source can introduce substantial
proportions of hardness (calcium salts) into the washing
liquor.
10 gram samples of the formulas shown in Table II were
made using a hand driven lab press at 6000 pounds of pressure
with a press time of 30 seconds. We conducted a wicking test
performed by placing tablets in 5 grams of dyed water (Sudan
IV dye) in a watch glass and noted tablet condition at
various time intervals. The tablets were monitored for 10
minutes and the tablet appearance was noted. In particular,
we looked for swelling, cracking and disintegration, chemical
bubbling and exotherm.
WO 94/19447 ~ ~~ PCT/US941001~9
16
0
N
A
O
.r
O
N
w
O
N
O
P~
O
,
w
0
'.
r~
N
t~
~n b
o
U '~7
N
U
ri
N
t01
O
,..~ 1
~O
O
O
O
w1
O
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O
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O
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O~
00
1~
O~
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~ O
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~
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WO 94/19447 - ~ ~ PCT/US94/00189
17
Sample No. 1 having 10 wt~ of encapsulated halogen source
absorbed water and generated cracks in its mass. However,
the tablet did not crumble indicating the tablet could
withstand distress of dispensing. Tablets 3 and 5 after
immersion generated small cracks but were intact after 10
minutes showing that they are adequate for controlled
dispensing. Tablets 7 and 9 containing 5-10 wt~ of methyl
ether of polyethylene glycol casting agent cracked and showed
evidence of thermal instability. Tablets 11 and 13
containing anhydrous sodium metasilicate and binder bubbled
and exothermed showing the unsuitability of metasilicate as a
binder. Tablet 15 containing sodium tripolyphosphate (light
density) was very hydrophilic, absorbed substantial
quantities of water and crumbled completely indicating its
unsuitability for accurate controlled dispensing. Tablet 29
containing sodium zeolite similarly disintegrated completely.
Tablet 37 containing 10 wt~ of a polyacrylic acid composition
failed to form an adequate solid tablet upon compression.
Tablet 39 containing 10 wt~ of britesil silicate absorbed
water, cracked and swelled causing some degree of
disintegration indicating its unsuitability for controlled
dispensing. Tablet 41 containing linear alkyl sulfonate
cracked and retained substantial quantities of water on
dispensing. Tablet 66 containing 2.5 wt~ drakeoil did not
absorb water initially but did absorb some small part of
water, but was hydrophobic and failed to dispense adequate
amounts of halogen source. Tablet 69 cracked and retained
water indicating its general unsuitability for dispensing
controlled amounts of chlorine.
From this data and other experiments we have conducted
with the shaped solids containing the encapsulate source of
halogen used in this invention shows that the use of the
encapsulated halogen source provides two important qualities
to the shaped solids of the invention. First, the halogen
source acts as a binder material that permits the manufacture
of the shaped solids in an efficient manner resulting in a
mechanically stable, useful solid. Further, the encapsulated
CA 02151475 2004-05-06
- 18 -
chlorine source permits the controlled dispensing of halogen
bleach into a bleaching/cleaning locus. We have found that
a number of the other binders, active cleaning agents,
surfactants, etc. can be used in making the tablets of the
invention, however, only the encapsulated chlorine source
provides all of the characteristics required for a
mechanically stable tablet, ease of manufacture, controlled
dispensing of chlorine and high active bleaching without
chemical incompatibility.
In one embodiment, the shaped cylindrical solid may
have a thickness of about 10 to 80 millimeters (0.393 to
3.150 inches) and a diameter of about 20 to 150 millimeters
(0.787 to 5.91 inches) with an encapsulate being evenly
dispersed throughout the solid phase. The encapsulate is an
active halogen source with at least one encapsulative layer.
The solid may have a mass of at least 1 gram and the
encapsulate having a diameter no greater than 5 millimeters
(0.197 inches). The source of active chlorine (one
possibility for the active halogen bleach) may be
chlorinated trisodium phosphate, chlorinated sodium
tripolyphosphate, or mixtures thereof.
As a further embodiment, the particle size of the
continuous solid phase of the shaped solid may be about 0.2
to 5 millimeters, (0.008 to 0.197 inches). The solid may
also contain a wetting agent. The solid may further contain
a sequestrant. The wetting agent, as well as the
sequestrant, may be part of the continuous solid phase of
the solid. The continuous solid phase may also contain a
diluent.
The above specification, examples and data provide for
a basic understanding of the invention. However, since many
embodiments of the invention can be made without departing
from the spirit and scope of the invention, the invention
resides in the claims hereinafter appended.
