Note: Descriptions are shown in the official language in which they were submitted.
t . , . 2 018 79 ~ c 6087 (R)
BLEACHING ARTICLE AND COMPOSITIONS
This invention pertains to the field of bleaching
articles and compositions for use in washing laundry articles.
BACKGROUND OF THE INVENTION
`~ Bleaching products for use in laundering of fabrics
~ol.~e..~ionally have been sold in the form of powders and liquids.
Consumers have thus been required to measure appropriate dosages
from containers holding these products each time they wish to
bleach a load of laundry. This measuring process has several
drawbacks which are perceived by consumers as rendering liquid or
powder bleach inconvenient: the liquid or powder products are
easy to spill and not simple to measure accurately. Moreover,
consumers usually use about the same amount of bleach for each
wash; thus, remeasuri~g the amount they desire repeats a step
per~ormed many times before. Bleach compositions have the
additional problem that bleach activity is lost over time; this
is especially so for chlorine bleaches in an aqueous liquid.
Liquid bleach compositions in several forms are known,
e.g. liquids, powders or pastes (U.S. Patent 4,105,573). It has
sometimes been deemed desirable to thicken liquid bleaches.
-1- ~
2 018 79 6 c 6087 (R)
Bleach composition thickeners have included clay, alone or
combined with certain polymers (U.S. Patents 4,116,849 and
4,116,851) as well as with mixtures of detergents (U.S. Patent
4,337,163); cellulose derivatives and colloidal silica (U.S.
Patent 4,011,172).
Delivery of bleach to a washer is made somewhat simpler
by use of a pouch. Dry particulate bleach has thus been added in
water-soluble film packets (U.S. Patent 3,644,260) as well as in
porous pouches (U.S. Patent 4,286,016~. Indeed, U.S. Patents
4,638,907 and 4,659,390 disclose adding several cleaning actives
at once, between two layers of polymeric material laminated
together, in a product which segregates each active from the
others.
Less common than pouch-delivery of bleach has been
delivery of dry chlorine bleach particles by water-soluble sheets
(U.S. Patent 4,532,063; 4,557,852 and 4,654,395).
There has been little use of non-water soluble sheet
delivery systems for bleach. Applicant believes such systems may
afford significant benefits over the art.
Yet certain disadvantages arise with single she~t-type
2 Q 1 8 7 9 ~ C 6087 (R)
laundry articles. Thus, some substrates are weakened and torn
apart by washing, leaving unpleasant pieces to be removed from
laundry by the ronCllmer. Many substrate materials for carrying
the bleach composition are not bleach-stable and thus
disintegrate during storage or become unattractive to use. The
requirements of mechanical and bleach stability restricts the
substrate materials which may be used.
Even if the substrate is bleach stable, the composite
bleaching article should retain its pleasant feel and texture
during storage. Some articles lose their pleasant feel and
become brittle due, it is believed, to adsorption of ambient
moisture. The need to impart a lasting hand and resilience to
the bleaching articles also affects the substrates, as well as
the chemical compositions, which may be used.
There are further difficulties in processing single
sheet-type laundry articles. For example, the bleach composition
applied to the sheet should preferably be a viscous material
which does not tend to run off the substrate. Additionally,
aqueous chlorine bleach compositions have insoluble bleach
particles which may not be easily suspended. Syneresis in the
bleach composition to be applied to the substrate thus may cause
uneven bleach doses from sheet to sheet
~ ~ ~ r ~0 I g7g6 c 6087 (R)
Accordingly, it is an object of the present invention to
provide a bleaching article ir the form of a bleach-carrying
substrate which is flexible when handled, and has a pleasant
supple feel rather than a wet, greasy or tacky feel.
It is also an object of the present invention to provide
an effective bleaching article for use in an automatic washing
machine for laundry fabrics.
Another object of the invention is to provide a
bleaching article that is simple to manufacture and convenient to
store.
It is a further object of the present invention to
provide a bleaching article which does not suffer from loss of
bleaching activity and does not suffer physical damage in storage
or in use. Physical damage includes shredding of the substrate
in the wash as well as substantial flaking off of bleaching
composition from the substrate surface.
It is yet another object of the invention to provide an
aqueous bleach composition which does not suffer from ph~se
separation and may be applied to a flexible substrate.
-4-
201 879~
SUMMARY OF THE lNV~;N'l'ION
In one embodiment of this invention, an aqueous liquid
bleach composition comprises 20-90% of chlorine bleach
compound, 2-50% of a bleach stable dispersant which is an
oligomeric or polymeric polyanionic material, the amount of
the bleach exceeding the amount of the dispersant and the
composition being in the form of an aqueous slurry having a
pH of 5 to 8. The viscosity is from 100 to 100,000
centipoises at 25C, preferably from 500 to 6,000
centipoise. The slurry may be further thickened by an
alkali metal salt.
The aqueous slurry may further comprise 2-35% of a
cobinder material which contributes to binding undissolved
particles of bleach to a flexible substrate. The slurry
may further optionally include 0.1-10% surfactants and
0.1-10% fluorescent whitening agent.
A bleaching article for use in laundry cleaning is
provided and comprises:
a) water-insoluble flexible substrate,
b) a bleaching composition carried on said
substrate, said composition comprising 20 to 90% by weight
of a chlorine bleach and 2 to 50% by weight of a bleach
stable dispersant which comprises an oligomeric or
polymeric polyanionic material, the amount of the bleach
exceeding the amount of the dispersant.
A-`
2 Q 1 8 7 ~
It is important that the components of the slurry and
bleaching article are bleach stable. Suitable dispersants,
cobinders, substrate materials, etc. are identified as bleach
stable by having ignition temperature (defined below) of at least
150C, chlorine scavenging half life (defined below) of over 24
hours and chlorine capacity ratio (defined below) of less than
10% of their weight.
Once the liquid bleach composition has been dried to
the substrate, the level of water of hydration adsorbed by the
bleaching article depends on ambient humidity conditions and
the composition of the dried bleaching composition. Certain
suitable components of this composition (e.g. the dispersant or
cobinder) are hygroscopic and may absorb waters of hydration from
ambient humidity. A preferred embodiment has dispersant and
"~
201g 796 C 6087 (R)
cobinder components which have relatively little hygroscopicity.
A method of bleaching laundry and/or fabrics is further
an aspect of the present invention: in this method, the
bleaching article described above is placed in the washing
machine with laundry and run through the full wash cycle. The
bleach slurry material dried on and into the substrate dissolves
or ~ cociates from the substrate to release active chlorine
into the wash water.
DETAILED DESCRIPTION OF THE INVENTION
An aqueous bleach slurry composition may include 20-90%
chlorine bleach, or 30-70%, or 35-65%. (Unless otherwise noted,
all percentage amounts in this specification indicate % by
weight.) The amount of bleach in the slurry may be chosen to
deliver a certain amount of bleach to the wash.
Chlorine Bleach
The chlorine bleach compounds suitable for the thickened
aqueous slurry should have low water solubility and good bleach
performance on a weight basis. Suitable types of bleach~
compounds include chlorinated isocyanurates and halo hydantoins.
2 0 1 ~ 7 9 6 c 6087 (R)
Suitable chlorinated isocyanurates include sodium
dichloroisocyanurate and its dihydrate ("NaDCC"), potassium
dichloroisocyanurate, trichloroisocyanurate and the like. One
commercially available sodium dichloroisocyanurate dihydrate
which may be used in the slurry is CDB Clearon, ex Olin Corp.,
sold as a powder with particle size of from about 1 to about 200
microns. Among the halo hydantoins suitable for the slurry are
dialkyl hydantoins, alkylaryl hydantoins or diaryl hydantoins.
More particularly, these include 1,3-dichloro-5,5-dimethyl
hydantoin ("DCDMH"), N-monochloro-5,5-dimethylhydantoin,
methylene-bis 1,3-dichloro-5-methyl-5-n-isobutylhydantoin,
1,3-dichloro-5-methyl-5-n-amylhydantoin, bromochloro-5,5-dimethyl
hydantoin ("BCDMH") and the like.
Other useful bleach compounds are trichloromelamine,
N-chloromelamine, monochloramine, dichloramine, paratoluene
sulfondichloroamide, N,N-dichlorooxodicarbonamide, N-chloroacetyl
urea, and N,N-dichlorobiuret, chlorinated dicyandiamide,
dichloroglycoluril, N,N-dichlorobenzoylene urea, and
N,N-dichloro-P-toluene sulfonamide and mixtures, etc.
The aqueous slurry has pH of about 5-8. As demonstrated
in Example 1 below, at preferred pH 5 5 to 7.5, bleach h~f life
is nearly doubled over the half life at pH 5Ø And at ~ost
' C 6087 (R)
- 20fg7'g6
preferred pH 6.0 to 7.0, bleach half life is triple that at pH
5Ø
The thickened bleach composition may comprise several
c~mponents in addition to bleach and water. But because the
bleach slurry is more harsh than commercial caustic chlorine
solutions (owing to the higher available chlorine concentration),
and the neutral pH increases reactivity of free chlorine,
hypochlorous acid and its salts, many compounds are not stable
in such an environment. If components chosen are not
bleach-stable, they may impair production of the bleach slurry,
or render it unattractive or non-functional.
Three tests were developed to identify components which
are compatible with the strongly oxidizing slurry: the ignition
test, the chlorine scavenging test and the the chlorine capacity
test, described in Examples 4 and 5 below. Satisfactory results
for each of the tests are indicated in these Examples. However,
it should be noted that a satisfactory result in one test does
not indicate a component has bleach stability; rather, one must
consider the results of all three tests.
Aside from such cosmetic and operational consid~rations,
the bleach slurry and article require care in manufacture to
~ 7 9 6 C 6087 (R)
avoid the risk of exothermic reactions. Ammonium compounds must
not be used under any circumstances in the bleach slurry since
they can give rise to chloramines. Of particular concern is the
accidental use of the common ammonium salts of polymeric acids.
Trichloramine is one of the most significant hazards faced when
working with chlorine bleach. The chlorinated isocyanurates will
generate chloramines in the presence of ammonia or ammonium salts
or on their own in high concentrations at 10 < pH < 5. Other
nitrogen compounds should also be avoided. Experience has shown
that violent decomposition may occur without warning.
Dispersant Material
The bleach slurry further includes 2-50% by weight of a
dispersant material. The dispersant acts to reduce solubility of
the bleach, thereby salting out chlorine bleach. The result of
this salting out is to increase the level of insoluble chlorine
bleach in the slurry, thus increasing the viscosity of the
slurry. Several dispersant materials also contribute to binding
the dried slurry to the substrate in bleaching articles described
below.
Suitable dispersants are those which have satisfactory
ignition temperature, chlorine scavenging half life and ~hlorine
-10-
2018796 c 6087 (R)
-
capacity as defined in Examples 4 and 5. These dispersants
include: oligomeric or polymeric polyanionic materials.
These materials may be straight chain or branched. Suitable
polymeric materials include-homo- and copolymers of acrylates,
methacrylates, maleates, vinyl acetate, styrene and sulfonated
styrene. Copolymeric materials may have regular or block
structures. Further suitable polymeric materials include
sulfonated polystyrene-co-maleate and polyvinyl sulfonate.
Preferred dispersants include polyacrylates and copolymers of
acrylic and maleic acid.
The molecular weight of the polymeric polyanionic
dispersants should be from about 1,000 to about 100,000, with
weights of about 5,000 to about 50,000 being preferred.
Suitable oligomeric materials include homo- or
co-oligomers of the monomeric materials identified above, and
should have molecular weights of about 200 and 1,500. A suitable
commercially available product is Belclene (ex Ciba Geigy), an
oligomer of maleic acid available in molecular weights of 400-600
and 600-800.
Several inorganic salts may be used as auxiliary~
dispersants in the slurry. The greater solubility of thése salts
7g~ C 6087 (R)
further reduces the solubility of the bleach. These salts
include alkali or alkaline metal salts of mono-phosphates,
sulfates, phosphonates and sulfonates. Potassium salts have the
surprising ability to impart significantly greater viscosity,
especially in combination with polymeric dispersants. Common
dispersant materials such as polyphosphates are unsuitable
because they have low solubility with respect to chlorine bleach.
For example, when sodium dichloroisocyanurate is added to a
solution of sodium diphosphate, the latter crystallizes out of
solution. Sodium chloride is also unsuitable since chloride
accelerates loss of chlorine bleach activity.
The preferred dispersant materials are the polymeric
polyanionic compounds. These have ~een found to impart lowered
solubility to the bleach in the slurry. The resulting higher
viscosity is due, it is believed, to the greater amount of
insoluble bleach and, in part, the polymeric dispersant
molecules (see Example 3 below). But the polymeric dispersants
also impart phase stability to the slurry: these dispersants help
disperse the bleach particles in the slurry and prevent
unattractive settling out, as demonstrated in Example 2.
Depending on the amount of dispersant added, th~ slurry
viscosity may range from lOo to lo,oO0 centipoises, at 2~C as
2~1~796 c 6087 (R)
measured with a Haake Rotovisco viscometer model RV-3 and either
an MK-S0 or MK-500 measuring head and an MVl and SV1 cup and
spindle. It is preferred that slurries have viscosity less than
6,000 centipoises for easy pouring; viscosities of less than
3,000 are more preferred, with viscosity from 500-1,500 imparting
desirable pouring speed with attractive rich consistency to the
slurry. The viscosity of the bleach slurry is examined in
Examples 6.
Examples 1, 2 and 3 which follow illustrate the effect
of neutral pH and dispersant level on bleach activity and
physical stability of the bleach slurry.
C 6087 (R)
~0~79~6
EXAMPLE 1
The bleaching strength of an aqueous solution containing
a chlorine bleach is expressed in terms of available chlorine.
This strength, or oxidizing power, of the solution is measured by
the ability of the solution to liberate iodine from an acidified
iodide solution in a standard iodometric titration. This
oxidizing power normally diminishes the longer dry chlorine
bleaches are exposed to water, and can even be lost when most of
the chlorine bleac~ is present as suspended particles.
Buf~ered aqueous solutions of 5% sodium polyacrylate
(molecular weight 10,000) at pH values of 4.2, 4.9, 5.3, 6.0,
6.8, 7.0, 7.2, 7.4, 7.5, 7.7, 7.8 and 8.3 are made. Sodium
dichloroisocyanurate dihydrate is added to give a concentration
of 2000 ppm av. C12 in each solution. By performing iodometric
titration of acidified aliquots periodically, the half life of
chlorine in each solution is determined. At pH 4.3 and 8.2, half
life is only about 50 hours. As Fig. 1 shows, in the presence of
a polyanionic dispersant, the half life rises significantly
between pH 5-8, is quadrupled at pH of 5.5-7.5 and quintupled at
pH of 6.0-7Ø These are significant increases in half life: at
preferred pH of 5.5 to 7.5, half life is nearly double that of pH
5.0, while at most preferred pH 6.0 to 7.0, half life is tripled.
' C 6087 (R)
2G1~79~
EXAMP~E 2
The role of the dispersant as a stabilizer of the slurry
is seen in the following test, where six 200 g slurries are mixed
with 107 grams of bleach and different amounts of water (42-67
grams) and polyacrylate dispersant (51-26 grams of LMW-lOON ex
Rohm & Haas Corp., neat polymer molecular weight 10,000). The
slurries are mixed well with a glass stirring rod and then
transferred to 250 ml graduated cylinders with ground glass
stoppers. Twenty four hours after mixing slurries 1 through 6,
the settling of bleach particles in each is read by measuring the
total slurry volume (vt) and the volume of clear supernatant at
the top of the slurry (Vs). The percentage of the total slurry
which forms clear supernatant indicates the volume of slurry from
which bleach has settled.
C 6087 (R)
2018796
. % by weight
Slurrv Components of slurry Vt (in mls) Vs (in mls) Vs/Vt (%)
1107 g bleach S3.5 115 6 4.7
42 g water 36.3
51 g polyacrylate 10.2
2107 53.5 127 8 6.1
47 37.3
46 9.2
3107 53.3 132 11 8.6
52 36.3
41 8.2
4107 53.5 128 13 9.8
57 39.3
36 . 7.2
107 53.5 132 15 11.4
62 40.3
31 6.2
6 107 S3.5 132 17 12.9
67 41.3
26 5.2
As the amount of dispersant falls from 10.2 to 5.2
weight %, there is a corresponding increase in the amount of
phase separation from 4.5 to 12.9 supernatant volume %. This
shows that polyacrylate dispersant increases phase stability of
the chlorine bleach slurries.
Bleach sheet articles are prepared in a fume hood by
painting the day old slurry onto swatches of International Paper
9335064 polyester nonwoven. The articles are evaluated after
-16-
C 6087 (R)
201879~
drying over night at ambient 27% relative humidity.
Dispersant
in original slurry
(wt %) Sheet Evaluation
10.2 excellent, flexible, very low dusting
-~- 9.2 good, flexible, low dusting
8.2 fair, dusty, limited web penetration
7.2 fair, similar to 8.2~ formulation
6.2 unacceptable, too dusty
5.2 unacceptable, too dusty
Thus, the greater the amount of dispersant, the more
retentive is the dried slurry to the substrate.
2~187 9 6 C 6087 (R)
E~AMPLE 3
Three slurry compositions are made with the following
ingredients: -
A B C
30 g NaDCC bleach 30 g NaDCC bleach 30 g NaDCC bleach
1~-10 g polyacrylate 10 g polyacrylate 10 g polyacrylate
50 ml water 50 ml of lM 50 ml of lM
Na phosphate K phosphate
pH 7 pH 7 pH 7
The compositions A-C are made by adding water to a
vessel, followed by phosphate salt if any, then polyacrylate and
finally bleach.
Each of the three bleach slurries is tested for the
amount of chlorine present in the aqueous phase only. This is
done by standard iodometric titration. The following levels of
available chlorine are found:
-18-
201~796 C 6087 (R)
~ B C
5.5% av Cl2 4.1% av Cl2 1.5% av Cl2
(10~ bleach) (7% bleach) (3~ bleach)
Usually, NaDCC is soluble in water up to about 35~.
Thus, the dispersant polyacrylate alone reduces the amount of
available chlorine in the aqueous phase of the slurry down to
only about 10%. Phosphate salts, especially potassium phosphate,
reduce the level even more, and can even be seen to increase the
viscosity significantly.
Cobinder
While the polyacrylate acts as a binder for the bleach
particles when dried, the slurry may further include an adhering
substance, and further reducing the level of dusting by dried
slurry from substrates. The adhering substance is believed to
play a role in binding the undissolved bleach particles to the
substrate. Suitable adhering substances, or "cobinders" have
satisfactory ignition temperature, chlorine scavenging half life
and chlorine capacity and include latexes.
(As will be discussed belo~, some substrates are
-19-
~ c 6087 (R)
201~796
composed of fibers held together by a resinous substance. The
resinous substance, usually called a "binder", is present on the
substrate fibers when received from the manufacturer. In this
application, the term "co-binder" is used as a synonym for
adhering substance, and is not to be understood, except for the
circumstances explained below, as a binder material on a
substrate.)
It is desirable to incorporate one or more cobinder
materials into the bleach slurry for several reasons. The
cobinder improves retention of the dried slurry to the substrate
during storage. Also, cobinders such as film forming latexes
have significantly lower hygroscopicity than many of the suitable
dispersant materials (e.g., polyacrylate). Thus, a slurry, and
bleach sheet articles coated therewith, having a blend of
dispersant and co-binder, absorb less ambient humidity. In
addition, latexes with low glass transition temperature (Tg) are
more flexible and less brittle than polyacrylates and thus
contribute to a better "hand" for the bleach sheets.
The bleach slurry may include 2-35~, preferably 5-30%
and most preferably 8-25~ co-binder.
-20-
' . C 6087 (R)
2018796
Surfactant
The bleach slurry may be formulated without surfactant:
added directly to the wash the slurry bleaches well. Moreover,
the 81Urry readily penetrates substrate materials despite the
hydrophobic character of polyester and polyolefin substrates.
Nevertheless, certain surfactants improve wetting of the slurry
on the substrate and thereby assist application of the slurry to
a substrate and foster wetting of the sheet in the wash cycle.
Surfactants are selected based on their performance and
the bleach compatibility criteria used for dispersants (see
Examples 4 and 5). Suitable surfactants among the anionics
include Cg-C22 soaps; aryl sulfonates, available as Dowfax
surfactants ex Dow Chemicals; long chain (Cg-C22) alkyl sulfates
and sulfonates, and C6-Clg alkyl benzene sulfonates. These alkyl
groups may be straight or branched. Two commercially available
branched aIkylated anionics suitable for the bleaching article
are sodium heptadecyl sulfate (Niaproof 7 ex Niacet Corp.,
Niagara Falls, NY) and sodium 2-ethyl-hexyl sulfate (Niaproof 08
ex Niacet Corp.). Suitable nonionic surfactants include amine
oxides.
While soaps, Dowfax and alkylbenzene sulfonates may
-21-
. . C 6087 (R)
~I &7~
im~e substrate and bleach article wetting, they may also lead
to deleterious foaming under certain processing conditions.
Thus, levels of these materials should be minimiæed to 0.1-10%,
or preferably 0.5-5% surfactant, or most preferably 1-3%.
Surfactant amounts may be greater than 10~, i.e. up to 15 or 20%,
but such levels will not significantly improve results.
r-
~ . . .
Fluorescer
Fluorescent whitening agents may optionally be included
in the slurry. These are generally known to provide brightening
benefits in the wash. However, most fluorescent whitening agents
lose their activity in the presence of chlorine bleach, making it
difficult to deliver fluorescers from a bleach system. A few
special fluorescer materials, from the family of sulfonated
stilbenes are more resistant to oxidative degradation. These
,~- ~ *
A include Tinopal CBS-X and Tinopal RBS-200 (ex Ciba Geigy and
described in U.S. Patent 4,460,485, hereby incorporated by
reference) and Phorwhite BHC-766 (ex Bayer-Mobay~. Any
sulfonated stilbene fluorescer may be incorporated in the
bleaching composition, however, the three identified fluorescers
are preferred.
Phorwhite BHC-766 is the most effective of thesé
olenoteS trad~ r~a~1~
-22 -
C 6087 (R)
201879~
whiteners, ~ecause it loses less activity than Tinopal CBS-X, and
reacts less with the chlorine of the thickened bleach slurry than
RBS-200. Phorwhite BHC-766 has additional benefits in being
readily dispersible in the bleach slurry and retaining stability
under processing and storage conditions. The stability of
Phorwhite BHC-766 is attributed to low reactivity and low
solubility in the aqueous phase of the slurry. (See Example 7
below.)
The thickened bleach composition may contain from
0.01-10% fluorescing agent, or 0.5-5% or 1-3%.
A preferred embodiment of the bleach slurry comprises
40-60% chlorine bleach, 4-18% dispersants and binders, 0-10%
fluorescer and 25-60% water.
Process of Makinq Slurry
The components of the aqueous bleach slurry may be mixed
in any order using conventional equipment for making aqueous
dispersions.
As indicated above, all the components of the sl~rry may
be added to the water base as liquid solution or suspension or as
-23-
C 6087 (R)
- 2018796
a solid. When one or more of the components are in liquid form
(as when LMW-lOON ex Rohm & Haas Corp., a 40~ solution of
polyacrylate is used), it is useful to add such liquid components
to the water base before adding any solid ones. This is because
some of the solid components may significantly increase viscosity
of the aqueous composition. Thus, for example, if powder
chlorine bleach is added to water, the slurry formed gradually
becomes more and more viscous. Mixing in liquid components prior
to making the aqueous composition becomes viscous assures
thorough dispersion of all components throughout the slurry.
Accordingly, a preferred method of stabilizing an aqueous bleach
compos-tion against phase separation comprises: adding 2-50% by
weight of a dispersant material to an aqueous base, neutralizing
this mixture to a pH of 5 to 8, and adding 20-90~ by weight of a
dry chlorine bleach to the neutralized mixture to form the bleach
slurry.
In mixing the liquid components into the water base,
conventional mixing machinery and techniques may be used; the
mixing should run as long as needed to impart substantial
homogeneity to the aqueous composition.
The addition of solid components may also be performed
using conventional mixing machinery techniques. However, it is
preferred to employ a high shear mixer, such as a Cowles mixer,
if solid bleach is added to the aqueous base. The high shear
imparted by this mixer is believed to mix the components better
than non-high shear mixers.
When solid components are added to the water or aqueous
-24-
C 6087 (R)
- 2018~796
base, it is preferred to add them gradually with constant mixing
to avoid clumping. It is even more preferred to add solid
components in constant weight amounts to the base followed by a
set amount of time to mix the newly added solid adequately into
the base.
Other components beside bleach may be added as solid,
for example, the fluorescing agent. When adding solid components
used in low amounts, it may be desirable to add them to the
aqueous base ~rior to the bleach. Such an order of addition may
mix the fluorescing agent more evenly through the entire slurry.
Alternatively, all the solid components may be combined
and mixed when dry then added to the aqueous base.
The Substrate
Substrates employed herein are wat~r-insoluble and are
solid or substantially solid materials. They can be dense or
open in structure, preferably the latter. Examples of suitable
materials which can be used as a substrate include foam, sponge,
paper, woven or nonwoven cloth. The absorbent capacity,
thickness and fiber density of the substrate are not limi~ations
on the substrate material which can be used herein, so lo'ng as
-25-
' C 6087 (R)
201879~
the materials exhibit sufficient wet-strength to maintain
structural integrity through the complete washing cycles in which
they are used. Substrate materials, like non-bleach components
of the bleach slurry, should have satisfactory ignition
temperature, chlorine scavenging half life and chlorine capacity
(see Examples 4 and 5).
The substrate may have any one of a number of physical
forms such as sheets, bloc~s, rings, balls, rods or tubes. It is
understood that the bleaching article described herein as a sheet
may be any of these alternate forms. Such forms are preferably
amenable to unit usage by the consumer, i.e. they should be
capable of addition to the washing liquor in unit amounts, such
as individual sheets, blocks or balls and unit lengths of rods or
tubes.
The nonwoven fabric substrates usable in the invention
herein can generally be defined as thermally bonded or adhesively
bonded fibrous or filamentous products, having a web or carded
fibre structure (where the fibre strength is suitable to allow
carding) or comprising fibrous mats, in which the fibres or
filaments are distributed haphazardly or in random array (i.e. an
array of fibres in a carded web wherein partial orientation of
the fibers is frequently present as well as a completely'
2 018 7 9 6 c 6087 (R)
hArh~7Ard distributional orientation) or substantially aligned.
The fibres or filaments can be natural (e.g. wool, silk, wood
pulp, jute, hemp, cotton, linen, sisal or ramie), synthetic (e.g.
rayon, cell~lose, polyvinyl derivatives, polyolefins, polyamides
or polyesters) or mixtures of any of the above. Examples of
materials suitable to carry the thickened bleach composition
include International Paper Co. code 9335064, a point-bonded
polyester fiber material; Scott 6724, a polypropylene fiber
material; Scott 6815, a polyester fiber material; and Reemay
2200, a polyester fiber material.
A preferred example of a thermally bonded nonwoven
fabric substrate is the point-bonded polyester nonwoven fabric
with weight of 1.2~ ounce per square yard available from the
International Paper Company, code 933S064.
However, it is noted that certain adhesive bonded
substrates are not suitable for the bleaching article. The
reason for adhesively bonding some substrates is that their
fibers are not amenable to thermal bonding and must be adhesively
bonded. When incorporated in the article, these substrates tend
to become brittle and crumble in storage or to collapse and
disintegrate in the wash, with the unpleasant result of ~eleasing
the thousands of fibers through the laundry. It is believed the
201~79G c 6087 (R)
undesirable brittleness and substrate disintegration are due to
incompatibility of the adhesive binder on the substrate with
bleach.
It is of course preferred that any adhesive bonded
substrate employed for the bleaching article be bleach-stable.
However, manufacturers of synthetic fiber substrate rarely
disclose which adhesive material they use on the substrates.
Thus, to identify substrates with bleach-stable adhesive binders,
the chemical compatibility tests described below in Examples 4
and 5 may have to be run. Alternatively, one may subject the
substrate material to mechanical and chemical compatability tests
described below.
(In some cases, the resinous binder holding substrate
fibers together may also help bind bleach particles to the
substrate. Dnly in these cases does the adhesive substrate
binder act as a "co-binderl' or adhering substance for the bleach
slurry. Generally, the bleach slurry applied to the substrate
should include cobinder to assure sufficient binding of particles
to the substrate. Resinous binders which are believed to help
bind bleach articles in this manner include urethane binders.)
While these fibers have usually appeared in adhésively
-2~-
C 6087 (R)
201 8796
-
honAe~ substrates only, they are now appearing in substrates
having blends of 2, 3 or more fiber types. A fiber blend may mix
rayon with a fiber usually thermally bonded, e.g. polyester.
Such substrates are also fully suitable for the bleach article
and include 7332, a polyester, rayon, and nylon mixed fiber
material; 7320, a polyester rayon mixed fiber material, Stearns &
Foster F-4334, a 50/50 rayon/polyester blend that is acrylic
resin bonded. Depending on the proportions of the fibers, the
entire substrate may be entirely thermally bonded with no
adhesive binder used at all.
A further class of substrate material that can be used
in the present invention comprises an absorbent foam like
material in the form of a sheet. The term absorbent foam-like
material is intended to encompass three dimensional absorptive
materials such as "gas blown foams", natural sponges and
composite fibrous based structures such as are disclosed in U.S.
Pat. Nos. 3,311,115 and 3,430,630 specifically incorporated
herein by reference. A specific material of this type is a
hydrophilic polyurethane foam in ~hich the internal cellular
walls of the foam have been broken by reticulation. Foams of
th~s type are described in detail in U.S. Pat. No. 3,794,029.
-29-
2 01~ 7 9 6 C 6087 (R)
~ he substrate should be mechanically and chemically
compatible with the bleach slurry and its processing and use
conditions. Substrate materials that are mechanically compatible
with conditions of use, i.e. which pass through the dryer cycle
substantially without damage are preferred, are those which do
not undergo minor changes in appearance during the wash cycle,
viz., pilling, pulling, tearing, etc. Mechanical compatibility
of the substrate is tested by subjecting a sheet substrate to
actual wash and dry conditions. A normal sized sheet about 9" by
11" sheet is added to a washing machine. The machine has a 17
gallon capacity and is loaded with 6 pounds of white cotton
ballast plus the sheet and a recommended amount of laundry
detergent (e.g., 97 grams of Surf). The wash cycle is run on hot
in 17 gallons of Edgewater, NJ municipal water at 130F for 15
minutes with a 5 minute rinse. The ballast with the sheet is
then added to a clothes dryer and dried at normal or high heat
settings. A polyester fiber substrate (Reemay 2200) survived
these steps intact while showing some pilling, while a 50/50
rayon/polyester resin bond substrate (Stearns F-4355)
disintegrated into a mass of shredded fibers. Other traits which
desirable substrate materials should have include suitable
softness and air porosity.
~.
The chemical, or bleach, stability of different'
-30-
C 6087 (R)
- 201 87~6
~ubstrate materials ~hould be determined by subjecting candidate
~ubstrate materials to the tests described in Examples 4 and 5 to
treatment with concentrated chlorine bleach in a fume hood. A 3"
by 3~ swatch of the substrate is soaked for one hour at room
temperature in one liter of an approximately 1000 ppm av. C12
hypochorite solution in 0.1 M phosphate buffer at about neutral
pH. The bleach solution may be about one-fiftieth dilution of
Clorox brand bleach. Phosphoric acid or aqueous sodium hydroxide
may be used to adjust pH of the solution. The swatch is then
removed from the bleach solution, squeezed dry and rinsed under
cold running tap water, and air dried.
A control swatch is soaked in one liter of water for an
hour at room temperature, then squeezed dry, rinsed and air
dried. The standard tensile strength of each swatch is then
measured. The tensile strenqth of the test and control swatch
may be determined by the test method set forth by the American
Society of Testing and Materials ("ASTM") in designation
D168-64(75) ~Breaking and Elongation of Textile Fabrics".
Substrates having tensile strength after the chlorine solution
treatment of at least about 6.5 lbs. in the machine direction
(MD) and deemed acceptable to bear the thickened bleach
composition in the bleaching article of the invention.
-31-
..~
2 018 7 9 ~ c 6087 (R)
In most cases, it is apparent which substrate materials
lac~ bleach stability: swatches of such material undergo
significant loss of tensile strength and may b~ pulled apart with
little effort while the control has all or most of the integrity
of a dry stAn~Ard swatch of the same material.
.~
Methods of making nonwoven cloths are not a part of this
invention and being well known in the art, are not described in
detail herein. Generally, such cloths are made by air or water
laying processes in which the fibres or filaments are first cut
to desired lengths from long strands, passed into a water or air
stream, and then deposited onto a screen through which the
fibre-laden air or water is passed. The deposited fibres or
filaments are then adhesively bonded together, dried, cured and
otherwise treated as desired to form the nonwoven cloth.
Nonwoven cloths made of polyesters, polyamides, vinyl resins, and
other thermoplastic fibres can be spunbonded, i.e. the fibres are
spun out onto a flat surface and bonded (melted) together by heat
or by chemical reactions.
Process of Makinq Bleachinq Article
,..~
The bleaching article may be made by any process which
C 6087 (R)
2018796
applies the slurry to the substrate such that the slurry is
substantially evenly distributed over the substrate for
impregnation thereof. The slurry-substrate complex is subjected
to drying so the resulting article feels dry to the consumer and
has no more than 30% free water. For good storage stability, the
article should have no more than 15% free water.
.
Conventional means for manufacturing the bleaching
article include coating the substrate with slurry via slot die
extrusion, reverse role coating, and dip and squeeze techniques.
Any series of steps which allows the substrate sufficient
residence time in the slurry (or exposure time to the slurry) to
substantially saturate the substrate is preferred.
Conventional means further include removing moisture
from the slurry-substrate complex, for example, by drying
processes such as air flotation, convection drying, infrared
drying and microwave drying.
It will be recalled that the chlorine bleach slurry is a
harsh corrosive substance. Thus, industrial machinery used to
manufacture the bleaching article will preferably be shielded
appropriately to protect parts susceptible to corrosion hy the
chlorine bleach. For example, rollers used in dip and squeeze
201~796 c 6087 (R)
te~niques resemble rollers used in paper-making. Rather than
having rubber or bare metal surfaces however, it is preferred the
roller surfaces exposed to the slurry have a thermoplastic or
Teflon~ coat. Similarly, if a doctor blade is used to scrape
excess slurry from the substrate, the blade may preferably be a
bleach-stable plastic, or metal rather than a corrodable metal.
In one method of making the bleaching article, the
bleach slurry is applied to nonwoven cloth by a method generally
known as padding. ~he slurry is placed into a pan or trough,
which may be heated if desired to provide desired fluidity. A
roll of absorbent substrate is then set up on an apparatus so
that it can unroll freely. As the substrate unrolls, it travels
downwardly and, submersed, passes through the pan or trough
containing the bleach slurry at a slow enough speed to allow
sufficient impregnatio,n. The absorbent substrate then travels,
at the same speed, onwardly and between a doctor blade and roller
or through a pair of rollers which squeeze off excess slurry.
The coated substrate is then dried by passage through a
convective air-impingement oven to dry the slurry-substrate
complex to a free-water level of about 8% plus or minus 7%.
After this drying step, the slurry-coated substrate can be
folded, cut or perforated at uniform lengths, and the fi~al
bleaching article then packaged and/or used.
-34-
2 01~ 7 9 6 C 6087 (R)
The preferred execution in this case is application of
the slurry using a slot-die applicator in which the bleach slurry
is pumped through a slotted orifice onto the moving web which may
be backed by a roller or other support. This process allows
direct application to the substrate providing good penetration
and has the advantage that the orientation of the applicator has
little impact on the coating application. In addition, the
coating level may be readily regulated to an extent by adjusting
the pumping rate to,the speed of the moving web. M~intaining the
slurry in a closed system until application avoids over
thickening resulting from evaporation of the fluid which may
occur when using an open pan. This method of application is
known primarily for the application of hot melt adhesives.
The Bleachinq Article
The amount of bleach delivered to the washing machine
depends on the size of the substrate carrying the dried slurry,
the amount of slurry coated on the substrate and the
concentration of chlorine bleach in the slurry.
The size and shape of the substrate sheet is a matter of
choice and is determined principally by factors associat~d with
-3~-
201~79~ c 6087 (R)
the convenience of its use. Thus, the sheet should not be so
small as to become trapped in the crevices of the machine or the
clothes being washed or so large as to be awkward to package and
dispense from the container in which it is sold. For the
purposes of the present invention, sheets may range in surface
area from 5 to 250 square inches. The preferred size range is
from about 80 to about 120 square inches.
The concentration of chlorine bleach in the slurry and
the amount of slurry on the substrate are also matters of choice
which may be determined mainly by convenience. Since many
consumers habitually use a liquid chlorine bleach, it is deemed
desirable that each bleaching article deliver an amount of bleach
comparable to some standard amount of liquid bleach. One
standard volume of liquid bleach consumers use is one cup
(English volume measurement); frequently, the amount of liquid
bleach added to a wash is a fraction or multiple of a single cup
of bleach. The bleaching article may be formulated so that one
cup (or fraction or multiple thereof) will be delivered by each
article. Thus, a unit dose of the bleaching article may contain
the amount of bleach in 0.05-2.0 cups of commercial sodium
hypochlorite solution, or preferably 0.1-2.0 cups and most
preferably 0.25-0.S cups. Since e~ch cup of commercial sodium
hypochlorite solution delivers about 180 ppm to the wash these
-36-
2 018 7 9 6 c 6087 (R)
volumes of bleach correspond respectively to 9 to 360 ppm,
preferably 18 to ~80 ppm and most preferably 45 to 90 ppm of
bleach delivered to the wash.
A highly preferred article herein comprises the chlorine
bleach compound in water-releasable combination with a sheet
which should be flexible so as to make it compatible with the
movement of the fabrics in the washing machine and to facilitate
its handling during manufacture and use of the product.
Preferably, the sheet is water permeable, i.e. water can pass
from one surface of the sheet to the opposite surface and, for
film type substrates, perforation of the sheet is desirable. The
most preferred form of the substrate is a sheet of woven or
~onwoven fabric or a thin sheet of open cellular plastic
material. Woven fabric sheets can take the form of a plain weave
natural or synthetic fibre of low fibre count/unit length, such
as is used for surgical dressings, or of the type known as cheese
cloth. Loading limitations on sheet type substrates limit the
amount of bleach that can be applied to the sheet namely to a
range represented by a slurry:sheet weight ratio of about 0.5:1
to about 40:1, preferably 1:1 to 20:1 and most preferably
2:1-lS:1. (See Example 8 below )
The following examples l~ill more fully illustrate the
-37-
201g796 C 6087 (R)
embodiments of the invention. As will be readily apparent to
persons of ordinary skill in the art to which the present
invention pertains, various modifications of such invention as
hereinbefore set forth and as further defined in the appended
claims may be made without departing from the spirit and scope
thereof..
,--
-
-3O -
2 018 7 9 6 c 6087 (R)
.
EXAMPLE 4
Ignition Tests
This example discusses the ignition temperature
of bleach slurry and bleaching article components.
Because many material~ undergo exothermic reaction at
elevated temperatures with ox~dants such as bleach, this
test is performed to identify components likely to cause
~uch runaway reactions.
~ In the test, a sample of equal parts by weight of a dry
bleach and a slurry or article component is formed. (Neat
samples of bleach are tested without any other component.) The
sample is then heated at about 3-5 C per minute,
and its temperature rise is recorded.
The ignition temperature (Ti) is arbitrarily defined as
that temperature at which the sample heating rate is
significantly greater than the applied heating rate, ie
over 10C per minute.
The following guidelines were used in evaluating the
safety of compositions.
Ti Interpretation
( C)
<100 Unsafe. Do not use.
>100 May be used with extreme caution on an
experimental scale Monitor samples
closely for any signs of reactions.
-39-
2 ~1~7 ~6 c 6087 (R)
dispose of unnecessary materials.
Additional testing and evaluation
necessary.
>120 Use with caution. May be scaled up if
sufficient experience is developed and
additional stability compatability
tests have been conducted.
>150 Unreactive. May be used with
appropriate caution.
It Fhould be noted that the Ti may vary for one component
depending on the bleach with which it is tested. Reactivity
of one component with one bleach may provide an indication of
reactivity with another; however, the Ti of a dispersant with
NaDCC may be within the unreactive range, but in the range of
caution or extreme caution with another bleach.
The apparatus used in these tests is shown in Figure 2.
The ignition test protocol is set forth more particularly as
follows. A l.S-lO.Og sample (Note 1) of the test material is placed
in a thick-walled 25x200 mm test tube. A thermocouple probe in a
protective PYREX glass sleeve is inserted into the sample which is
then lowered into a steel pipe in a sand heating bath constructed
from a heating mantle as shown in the Figure 2. A safety shield is
placed around the sand bath which is then heated at a rate of
3-5C/min (Note 2) by applying an appropriate fixed voltage while
the sample temperature was recorded. The test is halted when the
sample temperature exceeds 200~c
-40-
20187~6 c 6087 (R)
Note 1: The ~ample size may be varied depending on the intensity of
the thermal transitions and the potential hazards. The sensitivity
of the thermocouple, however, typically requires a minimum sample of
lg while samples greater than 5 g may present an unacceptable hazard.
Note 2: The heating rate of 3-5C/min is specified to complete tests
in 20-30 mins. and to minimize dissipation of exotherms by the
apparatus.
There follow ignition temperatures for several components
of the bleach slurry or the bleaching article.
Sample Description Sample Ti
Wt.(g) (C)
Neat NaDCC 2.S >200
Int. Paper polyester nonwoven #9335064 5.0 >200
LMW-lOON 3.0 >200
Phorwhite BHC-766, Bayer-Mobay 5.0 190
Ignition Temperatures for 1:1 NaDCC Admixtures
Sample Description Sample Ti
Wt.(g) (C)
Polymers
HPC, hydroxypropylcellulose 5.0 86
Polyvinyl alcohol 2.0 86
PVP K--6 0 5 ~ 9
Acrysol ASE-60 5.0 164
Rhoplex HA-8 5.0 166
NS-78-6312 5.0 141
-41-
2 0 1 8 7 9 6 C 6087 (R)
. ,
NS_78-6210 5.0 182
NS-78-6146 5.0 180
NS-78-6295 5.0 >200
SMA-1440A, poly(styrene-co-maleic
anhydride) derivatives:
Fully hydrolyzed S.0 154
n-octyl mon~ester S.0 106
EMA-1103, poly(ethylene-co-maleic
anhydride) derivatives:
Monomethyl ester, 10% esterifieq 2.0 170
n-Butyl ester, 10% esterified 5.0 164
Sodium isethionate ester, 10% esterified 3.0 >200
Solvents
Acetonitrile 20.0 140(1)
Isopropanol 20.0 >200
Methanol 20.0 100(3)
Ethanol 20.0 >200
Acetone 20.0 >200
Miscellaneous Materials
Cyanuric acid 5.0 >200
Urea 5 0 45(3)
Silwet 5.0 112
Melamine -- 140(3)
Ammelide -- 134(3)
Ignition Temperatures for 1:1 DCDMH Admixtur~s
Sample Description Sample Ti
Wt.(g) (C)
-42-
C 6087 (R)
79S~
Neat DCDMH -- >200
Polymers
HPC -- 52(3)
LMW-lOON 5.0 200
Tamol 850 -- 180
Tamol 960 -- 174
Monofax 1214 -- 100
' SMA-1440A n-octyl ester -- 100
EMA-1103 derivatives:
Hydrolyzed to the diacid 2.0 136
Methyl ester, 10% esterified 2.0 130
n-Butyl ester, 10% esterified 2.0 132
Sodium isethionate ester, 10% esterified 2.0 154
Miscellaneous Materials
Polyester substrate, Int. Paper 9335064 -- 194
Silwet 2.0 120
Ignition Temperatures for 1:1 BCDMH Admixtures
Sample Description Sample Tia
Wt.(g) (C)
Neat BCDMH -- 190
Polymers
LMW-lOON 10 150(1)
EMA-1103, fully hydrolyzed -- 180(3)
HPC ~ ( )
Silwet --' 140(3)
Lauryl alchol sulfate -- 100(3)
Talc 10 162(2)
-43-
7 9 6 c 6087 (R)
.
a) 3 - ~evere, 2 - strong, 1 - moderate, none - mild
Polymerc And Their Suppliers
Trade Name Description Supplier
Acrsol LMW-lOON Sodium
polyacrylate Rohm & ~aas
Acrysol ASE60 Acrylic copolymer emulsion Rohm & Haas
EMA 1103 Poly(ethylene-co-maleic anhydride) Rohm & Haas
NS-78-6146 Poly(acrylate-co-styrene) emulsion National Starch
NS-78-6210 Acrylic copolymer emulsion National Starch
NS-78-6295 Acrylic resin National Starch
NS-78-6312 Vinyl-acrylic copolymer emulsion National Starch
Rhoplex HA-8 Acrylic latex resin Rohm & Haas
Sokalan CP-5 Sodium poly(acrylate-co-maleate) BASF
Sokalan CP-7 Sodium poly(acrylate-co-maleate) BASF
SMA 1440A Poly(maleic anhydride-co-styrene) ARCO
Tamol 850 Polymethacrylate Rohm & Haas
Tamol 960 Polymethacrylate Rohm & Haas
Versa TL-3 Sodium poly(maleate-co-styrenesulfonate) National Starch
Versa TL-70 Sodium polystyrenesulfonate National Starch
-44-
- 2~1~796 C 6087 (R)
EXAMPLE S
-Reactivity Toward Aqueous Chlorine Bleach
The reactivity of material with chlorine bleach is an
important consideration in ~election of potential bleach slurry and
bleaching article components. The ignition tests in Example 4
provide an evaluation of compatibility of dry mixtures. Two
additional te~ts,nChlorine Scavenging" and "Chlorine Capacityn,
-: were developed to gauge the reactivity of chlorine bleach with
bleach slurry or article additives under conditions which mimic the
aqueous bleach slurry. These tests are primarily of use to
evaluate polymeri~ dispersants and binders but may also be used to
evaluate a variety of additives, such as surfactants.
Both tests are conducted at pH 7.0, nearly optimum for NaDCC
slurries. Sodium hypochlorite is used as the bleach instead of
NaDCC for convenience and because it is the actual active bleaching
agent generated by hydrolysis of the dissolved NaDCC.
Chlorine Scavenging
The chlorine scavenging test measures the rate of bleach
activity loss of sodium hypochlorite in a large excess of the
additive. This is, in a sense, a pseudo first order rate study.
The activity loss is monitored over a period of 3-4 half lives,
until it is <50 ppm av C12.
Separate solutions are prepared of about 200 ml of a 11.1 wt%
(or 5.6 wt%) of the material to be tested and sodium hypochlorite
at 5000 ppm av C12 in 0.2 M pH 7.0 phosphate buffer. A 20 ml
portion of the chlorine solution is added to a 180 g portion of the
test solution giving a mixture 10 wt% (or 5 wt%) in the test
-45-
` ~51~96 c 6087 (R)
material and 500 ppm av C12 as hypochlorite. The start time is
taken at the point when half of the stock chlorine solution has
been added. A separate blank solution is also prepared by adding
20 ml of the stock chlorine solution to 180 g of phosphate buffer.
Aliquots ~10-20 g) of the blank solution and the mixture are taken
at appropriate intervals and analyzed for changes in pH and
remaining activity by iodometric titration. The half lives for
chlorine bcavenging are determined from a plot of the percent
remaining activity verses time.
A blank solution shows almost no activity 10s8 while those
containing polymeric dispersants and binders have varying rates of
reaction as shown in the accompanying figure. Materials are judged
on the basis of their relative reactivities as measured by their
half lives (t~) listed in the table below. Unless otherwise noted,
the components are tested at a 10 wt% concentr~tion.
Polymer Chlorine Scavenging Half Lives
Component t1/2
LMW-lOON 5.5
LMW-lOON (5 wt%~ 24.0
LMW--lON 10.O
LMW-20N 0-3
LMW-45N 15.0
LMW-400N 5.5
Acrysol A-1 1.5
Acrysol A-3 <0 2
Acrysol A-5 <0 2
Sokalan CP-5 0.2
-46-
- . 2 ~ 6
C 6087 (R)
Sokalan CP-7 0.3
Sulfonated polystyrene 0.7
Ver~a TL-3 0.03
Ver~a TL-70 0.4
Narlex D-52 1.5
NS 78-6146 (5 wt%) 0.5
NS 78-6210 (5 wt%) 1.1
, NS 78-6312 (5 wt%) 1.5
Rhoplex HA-8 (5 wt%) 1.5
Polyacrylates as a group are seen to have the slowest rates
of reaction. Such slower rates of reaction are preferred. Many
potential dispersants and binders react very quickly. In some
ca~e6 rates of reaction are inconsistent with expectations based
on the compound~ structure. The curves of the activity 106S
versus time suggest that there is an initial fast reaction
followed by a much slower one. It was thought that the initial
rate is possibly due to the presence of highly reactive impurities
or additives such as surfactants used in the preparation of the
materials especially with latexes. A chlorine capacity test was
devised to determine, in effect, the amount of hypochlorite
required to neutralize these reactive materials.
Chlorine Capacity
The chlorine capacity test is conducted under similar
conditions as the scavenging test. sasically, a 5 wt%Isolution of
the polymer in 0.2 M pH 7.0 phosphate buffer is treated with
portions concentrated sodium hypochlorite solution until the
-47-
. ~018796 c 6087 (R)
reaction half life exceeds an acceptable value of 24 hrs., compar-
able to that of LMW-lOON.
More particularly, 200 g of a 5 wt% solution of the material
to be tested in 0.2 M pH 7.0 phosphate buffer is prepared and
treated with sufficient commercial sodium hypochlorite solution
(about 4 ml at 5 % av C12) to give a concentration of about 1000
ppm av C12. The test solution is evaluated after 24 hrs for any
change in p~ and remaining activity by iodometric titration of a 5
g aliquot. Th!e test is repeated by adding fresh portions of
sodium hypochlorite after daily analysis until the remaining
activity was >500 ppm av Cl2 or until six portions of hypochlorite
have been added. The amount of sodium hypochlorite which results
in a residual activity 2500 ppm av Cl2 is defined as the chlorine
capacity. Materials ~hich exhibit chlorine capacities >5000 ppm
av Cl2 or a chlorine capacity of greater than 10% are considered
unacceptable.
The results for several materials are listed below.
Chlorine Capacities
Component Chlorine Capacity
E~_ av. C12 Ratio (~)a
NS 78-6146 2600 5.2
NS 78-6210 2750 5.5
NS 78-6295 3100 6.2
NS 78-6312 >5000 >10
Versa TL-3 1800 3.6
Versa TL-70 2200 4.~
Narlex D-52 2200 4 . 4
Rhoplex HA8 3100 6. 2
-48-
~018 7g 6~ c 6087 (R)
~a) R~tio - (wt% av C12)/(wt% polymer)
Materials with chlorine capacities <10% of their weight are
considered acceptable for testing and evaluation unless other
test6, such as ignition studies prove negative. Caution must be
exercised ~ince the "neutralized~ component may pose a latent
hazard. Initial formulation studies should be conducted on as
small a scale as is practical with frequent-monitoring. The
polymers are generally pretreated with an amount of hypochlorite
defined by their chlorine capacities before use in bleach sheet
~lurry formulations.
WARNI~G: Normal precautions used in working with chlorine
bleaches should be employed when conducting these tests. Under no
c~rcumstAnces should amines, ammonium salts, or most other
nitrogen compounds be used since they potentially give rise to
extremely hazardous chloramines.
-49-
2 ~1&7 9 6 C 6087 (R)
EXAMPLE 6
The viscosity of several bleach dispersions was measured
on a Haake Rotovisco viscometer model RV-3 with either an MK-50
or an M~-500 measuring head and an MVl and SV1 cup and spindle.
The temperature was regulated using a Lauda RMS-6 refrigerat~ng
circulator with a claimed control accuracy of + or - 0.01C.
The viscometer was calibrated against standard oils and then the
bleach slurries were measured. The reported single value
viscosities were determined by shearing the slurries at a
constant shear rate of 80 per sec for 20-30 minutes after
which a steady shear stre~s was observed.
Powdered sodium dichloroisocyanurate ("NaDCC~) was added as
supplied by Olin Corp. to water and polyacrylate as indicated:
BleachPolyacrylate Water Viscosity
LMW-lOON
(Wt%) (Wt%) (Wt%)(cP at 25C)
68.0 4.0 28.0 3103
65.0 4.0 31.0 1310
60.0 5.0 35.0 683
59.5 12.0 28.5 6210
54.0 10.0 36.0 1187
54.0 5.0 41.0 144
46.0 13.0 41.0 583
45.0 5.0 50.0 100
40.0 13.0 47 0 241
-50-
201 g7g6! c 6087 (R)
EXAMPLE 7
Three fluorescent whitening agents are evaluated for
incorporation into the bleach slurry and sheet: Ciba-Geigy
Tinopal RBS-200 and CBS-X and Bayer-Mobay Phorwhite BHC-766.
CBS-X loses a signific~nt amount of activity when formulated with
the bleach slurry. RBS-200 also loses some of its fluorescent
activity during ~hort term processing. In comparison, BHC loses
no activity even under prolonged use, delivers excellent
brightening benfits, and is easy to incorporate into the standard
formulation with no changes. BHC is therefore used as the
fluore~cer of choice.
The evaluation of three commercial bleach-stable fluorescers
is by standard F-Dye tests (described in U.S. Patent 4,460,485
hereby incorporated by reference). Individually preweighed
mixtures of the fluorescer with 1.217 g of powdered NaDCC in
sample vials are provided for use in these Kleenette studies. The
pertinent results for the cummulative five wash fluorescence
effects are summarized in the tables below. The first table gives
the results for both high and low fluorescer concentrations using
dye-free liquid "alln. The high and low concentrations are
equivalent to 1 g and 0.1 g per normal wash dose (sheet),
respectively.
Fluorescer Performance in the Presence of 60 ppm Chlorine
~. ~ , . C 6087 (R)
2018796
Fluorescer Dose Monitor Cloth Type
(Supplier) q/3 gals. Cotton NylonDacron
Phorwhite BHC-766 0.176542.1 28.9 5.7
(Bayer-Mobay) 0.017722.6 15.7 4.2
Tinopal ~BS-200 0.277 36.4 31.3 25.7a
(57% active) 0.027723.2 18.2 6.1
(Ciba Geigy)
Tinopal CBS-X 0.176534.7 17.5 4.3
(Ciba Geigy) 0.0177 6.8 4.1 3.8
a)Yellowed.
20~79G c 6087 (R)
- EXAMPLE 8
A chlorine bleach slurry and a bleaching article are made
with the following formulation:
Component Slurry Wet Sheet Dry Sheet
81each - 51.2% 43.0% 55.4%
Dispersants
& Binders 11.2 9.4 12.1
Fluorescer 1.6 1.3 1.7
Water 36.0 30.2 10.0
Sub~trate --- 16.1 20.8
The bleach~ng article has a wet lpading ratio of about 5.2:1
and a dry loading ratio of about 3.8:1.
The bleaching article delivers 4.4 grams of active chlorine
(g av Cl 2) to the wash.
