U.S. patent application number 09/735954 was filed with the patent office on 2001-04-12 for peracid forming system, peracid forming composition, and methods for making and using.
This patent application is currently assigned to Ecolab, Inc.. Invention is credited to McSherry, David D., Wei, G. Jason.
Application Number | 20010000251 09/735954 |
Document ID | / |
Family ID | 23423653 |
Filed Date | 2001-04-12 |
United States Patent
Application |
20010000251 |
Kind Code |
A1 |
Wei, G. Jason ; et
al. |
April 12, 2001 |
Peracid forming system, peracid forming composition, and methods
for making and using
Abstract
A system for forming and releasing an aqueous peracid solution
is disclosed. The system includes a container and a peracid forming
composition provided within the container. The container is
permeable to the passage of water and aqueous peracid solution. The
peracid forming composition includes a peracid precursor and a
peroxygen source. Preferably, the peracid forming composition
includes a chemical heater capable of releasing heat upon
hydration. When placed in water, water enters the container and
interacts with the peracid forming composition provided within the
container. The water combines with the peracid precursor and
peroxygen source to provide an aqueous peracid composition. The
presence of a chemical heater within the container provides for the
generation of heat within the container which enhances the rate of
peracid formation. The peracid solution leaves the container and
forms an effective sanitizing amount of sanitizer. A composition
for forming and releasing an aqueous peracid solution is disclosed.
The composition can include a mixture of peracid forming components
or a composite structure containing peracid forming components
adhered together. Methods of sanitizing a surface having a
population of microorganisms are provided, and methods for
manufacturing are provided.
Inventors: |
Wei, G. Jason; (Mendota
Heights, MN) ; McSherry, David D.; (Minneapolis,
MN) |
Correspondence
Address: |
MERCHANT & GOULD
P O BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Ecolab, Inc.
St. Paul
MN
|
Family ID: |
23423653 |
Appl. No.: |
09/735954 |
Filed: |
December 13, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09735954 |
Dec 13, 2000 |
|
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|
09361843 |
Jul 27, 1999 |
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Current U.S.
Class: |
510/367 ;
510/370 |
Current CPC
Class: |
A01N 37/16 20130101;
C11D 3/042 20130101; C11D 3/3907 20130101; C11D 17/044 20130101;
A01N 37/16 20130101; A01N 25/14 20130101; A01N 37/16 20130101; A01N
2300/00 20130101; A01N 25/34 20130101; A01N 25/12 20130101; A01N
25/26 20130101; C11D 3/0052 20130101; C11D 3/3947 20130101; C11D
17/041 20130101 |
Class at
Publication: |
510/367 ;
510/370 |
International
Class: |
C11D 003/00; C11D
007/18; C11D 007/54; C11D 009/42 |
Claims
We claim:
1. A system for forming and releasing an aqueous peracid solution,
the system comprising: (a) a peracid forming composition
comprising: (i) a peracid precursor; (ii) a peroxygen source; and
(b) a container for containing said peracid forming composition,
said container being permeable to the passage of water and aqueous
peracid solution; and wherein the system, when immersed in water,
generates an aqueous peracid sanitizer solution having a pH of less
than about 8.
2. A system according to claim 1, wherein the peracid forming
composition further comprises a chemical heater capable of
releasing heat upon hydration.
3. A system according to claim 2, wherein the chemical heater is
provided in an amount sufficient to generate a temperature increase
within the container of at least about 5.degree. C. after immersion
of the article in water.
4. A system according to claim 1, wherein the system, when immersed
in water, generates an aqueous peracid solution having a pH of
between about 2 and about 4.
5. A system according to claim 1, wherein the peracid forming
composition further comprises an acid catalyst.
6. A system according to claim 5, wherein the acid catalyst
comprises sulfamic acid.
7. A system according to claim 2, wherein the chemical heater
comprises hydratable salt.
8. A system according to claim 7, wherein the hydratable salt
comprises a salt of an organic acid.
9. A system according to claim 7, wherein the hydratable salt
comprises a salt of a mineral acid.
10. A system according to claim 7, wherein the hydratable salt
comprises magnesium sulphate.
11. A system according to claim 7, wherein the hydratable salt
comprises an alkali earth metal salt.
12. A system according to claim 1, wherein the peroxygen source
comprises sodium perborate.
13. A system according to claim 1, wherein the peracid precursor
comprises carboxylic acid anhydride.
14. A system according to claim 13, wherein the carboxylic acid
anhydride comprises at least one of glutaric acid anhydride,
succinic acid anhydride, and maleic acid anhydride.
15. A system according to claim 1, wherein the peracid precursor
comprises carboxylic acid halide.
16. A peracid forming composition comprising: (a) about 2 wt % to
about 30 wt % of a carboxylic acid anhydride; (b) about 2 wt % to
about 30 wt % of a peroxygen source; (c) about 10 wt % to about 60
wt % a chemical heater capable of releasing heat upon hydration;
wherein the peracid composition is substantially free of liquid
water and is shelf stable.
17. A composition according to claim 16, wherein the carboxylic
acid anhydride comprises glutaric anhydride.
18. A composition according to claim 16, further comprising an acid
catalyst having a pKa of less than about 5.
19. A composition according to claim 16, wherein the chemical
heater comprises an alkali metal salt.
20. A composition according to claim 19, wherein the alkali metal
salt comprises an alkali metal salt of an inorganic acid.
21. A composition according to claim 16, wherein the chemical
heater comprises an alkaline earth metal oxide.
22. A peracid forming composition comprising: (a) a plurality of
composite structures, wherein the composite structures comprise
peracid precursor and peroxygen source adhered together in each
composite structure, and, when combined with water, said plurality
of composite structures generate an aqueous peracid solution having
a pH of less than about 8.
23. A composition according to claim 22, wherein said composite
structures further comprise a binder for holding the peracid
precursor and peroxygen source together.
24. A composition according to claim 23, wherein said binder
comprises at least one of alcohol ethoxylates, polymers containing
ethylene oxide, polymers containing propylene oxide, and polymers
containing both ethylene oxide and propylene oxide.
25. A composition according to claim 22, wherein said composite
structures further comprises a chemical heater capable of releasing
heat upon hydration.
26. A composition according to claim 25, wherein said chemical
heater comprises a hydratable salt.
27. A composition according to claim 22, wherein said composite
structures further comprise a moisture barrier coating around said
composite structure to restrict moisture vapor from contacting the
peracid precursor and the peroxygen source within said composite
structure.
28. A composition according to claim 22, further comprising a
moisture barrier coating around said peracid precursor to provide a
barrier between said peracid precursor and said peroxygen
source.
29. A composition according to claim 28, wherein said peracid
precursor having a moisture barrier coating comprises peracid
precursor which is liquid at a temperature of less than about
40.degree. C.
30. A composition according to claim 29, wherein the peracid
precursor comprises peracid absorbed onto an absorbent
material.
31. A composition according to claim 22, wherein the composite
structures are in the form of granules having an average diameter
of between about 0.2 mm and 2 mm.
32. A composition according to claim 22, wherein the composite
structures are in the form of tablets having an average diameter of
greater than about 2 mm and a size of up to about 200 grams.
33. A composition according to claim 22, wherein the composite
structures are in the form of a block having a size of greater than
about 200 grams.
34. A method of sanitizing a surface having a population of
microorganisms, the process comprising steps of: combining a system
for forming and releasing an aqueous peracid solution with water to
provide an aqueous peracid sanitizer solution, the system for
forming and releasing an aqueous peracid solution comprising: (a) a
peracid forming composition comprising: (i) a peracid precursor;
(ii) a peroxygen source; (b) a container for containing said
peracid forming composition, said container being permeable to the
passage of water and aqueous peracid solution; and contacting a
surface having a microbial population with the aqueous peracid
sanitizer solution for sufficient period to substantially reduce
the population of microorganisms on the surface.
35. A method according to claim 34, wherein the peracid forming
composition comprises a chemical heater capable of releasing heat
upon hydration.
36. A method according to claim 35, wherein the chemical heater
provides an increase in temperature within the container of at
least about 5.degree. C.
37. A method of sanitizing a surface having a population of
microorganisms, the method comprising steps of: combining a
composition for forming and releasing an aqueous peracid solution
with water to provide an aqueous peracid sanitizer solution, the
composition for forming and releasing an aqueous peracid solution
comprising a plurality of composite structures, wherein the
composite structures comprise peracid precursor and peroxygen
source adhered together in said composite structures, said aqueous
peracid sanitizer solution having a pH of less than about 8; and
contacting a surface having a microbial population with said
aqueous peracid sanitizer solution for a sufficient period to
substantially reduce the population of microorganisms on the
surface.
38. A method for manufacturing an article for forming and releasing
an aqueous peracid solution, the method comprising steps of:
providing a peracid forming composition within a container for
containing said peracid forming composition, said peracid forming
composition comprising peracid precursor and peroxygen source, and
said container being permeable to the passage of water and aqueous
peracid solution; and providing a moisture barrier envelope around
said peracid forming composition within said container to reduce
contact of said peracid forming composition with atmospheric
moisture.
39. A method for manufacturing a composition for forming and
releasing an aqueous peracid solution, the method comprising steps
of: adhering peracid precursor and peroxygen source together to
provide a composite structure comprising peracid precursor and
peroxygen source adhered together.
40. A method according to claim 39, further comprising a step of
coating said composite structures with a moisture barrier coating
for restricting moisture vapor into said composite structures.
41. A method according to claim 39, further comprising a step of
coating said peracid precursor with a moisture barrier coating to
provide coated peracid precursor prior to said step of adhering.
Description
FIELD OF THE INVENTION
1. The invention relates to a system for forming and releasing an
aqueous peracid solution; a composition for forming and releasing
an aqueous peracid solution; a method of sanitizing a surface
having a population of microorganisms; and a method for
manufacturing an article and composition. The system includes a
peracid forming composition provided within a container permeable
to the passage of water and aqueous peracid sanitizer solution. The
composition can be a peracid forming composition including peracid
precursor, peroxygen source, and chemical heater. In addition, the
composition can include composite structures which include both
peracid precursor and peroxygen source adhered together within a
composite structure. The method of sanitizing includes a step of
combining the system and/or the composition with water to generate
an aqueous peracid sanitizer solution and sanitizing a surface
having a population of microorganisms.
BACKGROUND OF THE INVENTION
2. Numerous classes of chemical compounds exhibit varying degrees
of antimicrobial or biocidal activity. Antimicrobial compositions
are particularly needed in the food and beverage industries to
clean and sanitize processing facilities such as pipelines, tanks,
mixers, etc. and continuously operating homogenization or
pasteurization apparatus. Sanitizing compositions have been
formulated in the past to combat microbial growth in such
facilities. For example, Grosse-Bowing et al., U.S. Pat. Nos.
4,051,058 and 4,051,059, teach peracetic acid materials. These
peroxy-containing compositions are known for use in the production
of microbiocidal agents. One such composition disclosed by
Grosse-Bowing et al. contains peracetic acid, acetic acid or
mixtures of peracetic and acetic acid, hydrogen peroxide, anionic
surface active compounds such as sulfonates and sulfates, and
water. Wang, U.S. Pat. No. 4,404,040, teaches a short chain fatty
acid sanitizing composition comprising an aliphatic short chain
fatty acid, a hydrotrope solubilizer capable of solubilizing the
fatty acid in both the concentrate and use solution, and a
hydrotrope compatible acid so that the use solution has a pH in the
range of 2.0 to 5.0.
3. Peracetic acid has been shown to be a good biocide, but only at
fairly high concentrations (generally greater than 100 part per
million (ppm)). Similarly, peroxyfatty acids have also been shown
to be biocidal, but only at high concentrations (greater than 200
ppm), such as in the composition disclosed in European Patent
Application No. 233,731. Antimicrobial compositions having low use
concentrations (less than 100 ppm) which effectively kill microbes
are particularly desirable. Low concentrations minimize use cost,
surface corrosion, odor, carryover of biocide into foods and
potential toxic effects to the user. Therefore, a continuing need
exists to provide such an antimicrobial composition for use in food
processing, food service and health care facilities.
4. Combining a peroxygen source with an acid precursor in forming
bleaching compositions or sanitizing compositions has been
disclosed in the prior art. The prior art compositions are often
formed in an aqueous solution which can be unstable, short lived,
corrosive, and difficult to contain due to a need to vent the
container containing the aqueous solution. Such compositions
require high purity because impurities can catalyze decomposition
of the peracid material. Aqueous solutions also require shipping of
water which increases costs.
5. U.S. Pat. No. 5,296,239 to Colery, et al. and U.S. Pat. No.
5,736,497 to Steiner describe aqueous liquid peracid sanitizer
formulations. International Publication No. WO 94/11483 describes
the use of acylated citrate esters and ethoxylated alcohols as
stabilizers. Solid mixtures are also known that generate peracid
upon dissolution in aqueous media U.S. Pat. No. 5,505,740 to Kong,
et al. describes in situ formation of peracid where the aqueous
wash solution is initially raised to a relatively high pH level by
introduction of an alkaline agent for enhancing production of the
peracid in the aqueous solution, then lowering the pH of the
aqueous solution for enhancing bleach performance.
6. Aqueous peroxygen solutions containing perborates and/or
hydrogen peroxide in combination with acids (e.g., boric acid) are
often stabilized by the addition of a stabilizing agent.
Stabilizing agents described in the prior art include carbazole
sulfonates, diphenylamine sulfanates, N-phenylamino naphthalene
sulfonates, and diethylenetriamine pentamethylene phosphonic acid.
See U.S. Pat. No. 5,736,497 to Steiner. This patent additionally
describes the stabilization of alkaline hydrogen peroxide solutions
by the addition of an organic stannate. U.S. Pat. No. 5,296,239 to
Colery et al. describes stabilizing a thickened peracetic
composition by adding sequestering agents, free-radical scavengers,
and mixtures of sequestering agents and free-radical
scavengers.
7. Techniques for enhancing performance of preformed peracids have
been disclosed by a number of prior art references. In particular,
U.S. Pat. No. 4,391,725 to Bossu discloses a granular hydrophobic
peroxyacid laundry product in the form of a preformed peracid
bleach provided within a pouch. An acid additive, indicated as
having a pKa of from about 2 to about 7, is combined with the
hydrophobic peracid in the pouch in order to aid in release of the
peracid from the pouch, thereby enhancing bleach performance. U.S.
Pat. No. 4,391,723 to Bacon et al. and U.S. Pat. No. 4,391,724 to
Bacon describe the inclusion of boric acid or other acids together
with the preformed peracids for improving bleach performance.
SUMMARY OF THE INVENTION
8. A system for forming and releasing an aqueous peracid solution
is provided by the invention. The system includes a peracid forming
composition and a container for containing the peracid forming
composition. The peracid forming composition includes a peracid
precursor and a peroxygen source. Preferably, the peracid forming
composition includes a chemical heater capable of releasing heat
upon hydration. The chemical heater can increase the local
temperature within the container by at least about 5.degree. C.
after the system is placed in water. The local temperature is
considered the temperature of the environment within the container.
The temperature increase is measured from the ambient temperature
of the water in which the system is immersed. The container is
permeable to the passage of water and aqueous peracid solution.
When the system is immersed in water, water flows into the
container, and the peracid forming composition generates peracid
which flows out of the container providing an aqueous peracid
sanitizer solution having a pH of less than 8.
9. The peracid precursor is preferably a component which is
relatively nonreactive with the peroxygen source under temperature
conditions normally found during transportation and storage.
Preferred peracid precursors which can be used according to the
invention include carboxylic acid anhydrides such as glutaric acid
anhydride, succinic acid anhydride, maleic acid anhydride and
mixtures thereof. The peroxygen source is preferably a component
which remains relatively nonreactive with peracid precursor under
temperature conditions normally encountered during the storage and
shipment. A preferred peroxygen source includes sodium perborate.
It should be appreciated that while the peracid precursor and
peroxygen source are characterized as relatively nonreactive toward
each other, this is under conditions of storage and transport. The
peracid precursor and peroxygen source are preferably very reactive
toward each other when combined with water (liquid or vapor). The
chemical heater can be any material which is compatible (preferably
nonreactive) with the peracid precursor and peroxygen source, and
which increases the temperature of the environment within the
container when combined with water. Preferably, the chemical heater
is included in an amount sufficient to increase the local
temperature by at least about 5.degree. C. after introducing the
system into water. Exemplary chemical heaters include hydratable
salts such as salts of inorganic and organic acids, salts of
mineral acids, magnesium sulphate, alkaline earth metal salts, and
alkali metal salts, and alkaline earth metal oxides.
10. A composition for forming and releasing an aqueous peracid
solution is provided by the invention. The composition can take
several forms. One form of the composition includes a mixture of
components. For example, the mixture can include about 2 wt % to
about 30 wt % of a carboxylic acid anhydride, about 2 wt % to about
30 wt % of a peroxygen source, and about 10 wt % to about 60 wt %
of a chemical heater capable of releasing heat upon hydration.
Another form of the composition includes a composite structure
which can take the form of granules, blocks, tablets, and the like.
The composite structure includes peracid precursor and peroxygen
source adhered together within the composite structure. A binder
holds the peracid precursor and peroxygen source together within
each composite structure. The peracid precursor can function as the
binder for holding the peracid precursor and peroxygen source
together within the composite structure. The binder can include
other components such as alcohol ethoxylates and polymers
(homopolymers and/or copolymers) of ethylene oxide and/or propylene
oxide. The composite structure can additionally include a chemical
heater, an acid catalyst, viscosity modifier, a moisture barrier,
and combinations thereof.
11. The composition can be referred to as a peracid forming
composition because it includes peracid forming components which
react, in the presence of water, to generate an aqueous peracid
solution. The composite structure and/or the mixture of peracid
forming components can be provided within the container permeable
to the passage of water and aqueous peracid solution. It is
expected, however, the composite structure will be used without a
permeable container. That is, the composite structure will be
applied to a wetted surface and the peracid solution will form on
the wetted surface. In contrast, it is expected that the mixture of
peracid forming components will generally be used to provide a
quantity of aqueous peracid solution which can then be used for
various applications.
12. Methods of sanitizing a surface having a population of
microorganisms is provided by the present invention. The method
includes a step of combining the system for forming and releasing
an aqueous peracid sanitizer solution with water, or combining the
composite structure for forming and releasing an aqueous peracid
sanitizer solution with water. The system can be used for
generating a volume of aqueous peracid sanitizer solution. This
solution can be provided, for example, in a bucket or container.
The sanitizer solution is particularly useful for use in hard
surface disinfection, potable water disinfection, fruit/veggie
sanitizing rinse, medical instrument sanitization, and kitchen
sanitization. The composite structure can be used by scattering the
composite granules on a wet surface which is to be treated. The
aqueous peracid solution is then generated on the surface. The
composite structure can preferably be used in various applications
including biohazard cleanup, carpet sanitization, floor
sanitization, and ostomy deodorization.
13. Methods for manufacturing a system for forming and releasing an
aqueous peracid solution and for manufacturing composite structures
for forming and releasing an aqueous peracid solution are provided
by the invention. The methods for manufacturing a system for
forming, and releasing an aqueous peracid solution can include the
steps of providing a peracid forming composition within a
container, and providing a moisture barrier envelope around the
peracid forming composition within the container. The moisture
barrier envelope is provided for reducing contact of the peracid
forming composition with liquid or vapor water. The methods for
manufacturing composite structures for forming and releasing an
aqueous peracid solution can include a step of adhering peracid
precursor and peroxygen source together to provide a composite
structure including both peracid precursor and peroxygen source
adhered together. The composite structure can include a chemical
heater and/or acid catalyst as part of the structure. In general,
the adhesion of the components together will be accomplished with a
binder. The peracid precursor can function as the binder. In
addition, a moisture barrier coating can be provided around the
composite structures, and/or around the peracid precursor
component, the peroxygen source components, or both components
separately.
BRIEF DESCRIPTION OF THE DRAWINGS
14. FIG. 1 is a partial cutaway, perspective view of a system for
forming and releasing aqueous peracid solution according to the
principles of the present invention;
15. FIG. 2 is a partial cutaway, perspective view of an alternative
embodiment of a system for forming and releasing an aqueous peracid
solution according to the principles of the present invention;
16. FIG. 3 is a diagramatic view of a composite structure for
forming and releasing an aqueous peracid solution according to the
principles of the present invention;
17. FIG. 4 is a diagramatic view of an alternative embodiment of a
composite structure for forming and releasing an aqueous peracid
solution according to the principles of the present invention;
18. FIG. 5 is graph showing the rate of peracid formation for test
compositions identified in example 1; and
19. FIG. 6 is a graph showing the temperature increase for test
compositions identified in example 1.
DETAILED DESCRIPTION OF THE INVENTION
20. The invention relates to a system for forming and releasing an
aqueous peracid solution. The system includes a container for
containing or holding the peracid forming composition, but which is
permeable to the passage of water and aqueous peracid solution. The
peracid forming composition is provided so that it remains
relatively stable during conditions of storage, but under
conditions of use, such as when liquid water is introduced into the
composition, the peracid forming composition generates an aqueous
peracid solution. The system and composition are preferably "shelf
stable" which means that under storage conditions of ambient
temperature, at least about 80 percent remains active after three
months. Preferably, at least about 80 percent remains active after
about six months. It should be understood that the level of
activity is based upon an activity of 100 percent immediately after
product formation.
21. When it is desirable to generate an aqueous peracid solution,
the system can be placed in a quantity of water. The water then
flows through the permeable container and contacts the peracid
forming composition resulting in the generation of aqueous peracid
solution which flows out of the container and into the surrounding
water. After a period of time, the quantity of water contains a
sufficient amount of peracid to provide an aqueous peracid
sanitizer solution for sanitizing the surface having a microbial
population.
22. The peracid forming composition can be referred to as a
self-heating peracid forming composition when it includes at least
one component which is responsible for the generation of heat.
Applicants have found that by providing localized heating, the rate
of peracid formation increases. A chemical heater can be used which
is activated by water and which increases the local temperature
within the container to increase the rate of peracid formation. A
preferred chemical heater is one which generates heat upon contact
of the peracid forming composition with water.
23. It should be understood that the phrase "aqueous peracid
sanitizer solution" refers to the aqueous solution which can be
used for sanitizing, disinfecting, and/or bleaching the surface of
a substrate. The aqueous peracid sanitizer solution can be referred
to more simply as the sanitizer solution or as the use solution.
Accordingly, the sanitizer solution can be provided with any
desired concentration of peracid sufficient to provide the desired
degree of sanitizing, disinfecting, and/or bleaching. The "peracid
forming composition" refers to the composition which, when combined
with water, generates sanitizer solution.
24. The peracid forming composition includes, as reactants, a
peracid precursor and a peroxygen source. The composition can be
provided in the form of a solids mixture, a combination of solid
and liquid, and as composite structure. In the case of a solids
mixture, the peracid precursor and peroxygen source are preferably
both provided as solids which do not react together until contacted
with water. The solids mixture includes a mixture of solid peracid
precursor, preferably in powder form, with solid peroxygen source,
preferably in powder form. When the composition is provided in the
form of a combination of solid and liquid components, the solid and
liquid components are preferably separated. For example, the liquid
component can be contained within a rupturable container. Once the
container is ruptured, the solid component and the liquid component
can react to form aqueous peracid solution. Alternatively, the
liquid component can be absorbed onto a substrate so that it can be
mixed with the solid component without substantially reacting with
the solid component. In addition, the liquid component which has
been absorbed onto a substrate can be coated with a moisture
barrier coating to help prevent reaction until the moisture barrier
coating is removed or penetrated. The composite structure contains
both the peracid precursor and the peroxygen source bound together
in a single construction. The composite structure can be provided
in the form of granules, blocks, tablets, and the like. When the
composite structure is contacted with water, the peracid precursor
component and peroxygen source component within the composite
structure react to form the peracid sanitizer solution. A component
of the composite structure can be a liquid component which has been
absorbed onto a substrate and optionally coated with a moisture
barrier coating to help prevent reaction until the moisture barrier
coating is removed.
25. Components in addition to the peracid precursor and peroxygen
source can be incorporated into the peracid forming composition.
The additional components include acid catalysts, chemical heaters,
viscosity modifiers, and binders.
26. An acid catalyst can additionally be incorporated into the
peracid forming composition to provide the aqueous peracid
sanitizer solution with a pH of below about 8 (and preferably below
about 7) and/or to increase the rate of forming aqueous peracid
solution. In general, pH values below about 7 are desirable for
providing a sanitizer solution capable of killing microorganisms.
It should be understood that reference to pH values refers to the
pH of the sanitizer solution or use solution. The pH value of a
peracid solution within the container may, at times, be relatively
acidic. The peracid solution flows out of the container and mixes
with the remaining water environment to provide a sanitizer
solution or use solution having a pH of below about 8.
27. It is advantageous for the components of the peracid forming
composition to remain solid under normal storage conditions. This
is particularly true when the peracid forming components are
provided in contact with each other within the permeable container
because it is desirable that the components do not react together
until contacted with water. Although a preferred embodiment of the
invention contemplates the entire peracid forming composition as a
solid composition, it is possible for at least one of the
components to be a liquid component. For example, the liquid
component can be provided within another container. Once the
container is ruptured, the contents thereof can then combine with
the remaining peracid forming components to generate peracid
sanitizer solution. The container can be ruptured by pressure such
as the pressure generated by a human hand. Alternatively, a liquid
component can be absorbed onto an absorbent or substrate which will
reduce reactions between the acid precursor and the peroxygen
source until water is introduced. Furthermore, the liquid component
absorbed onto an absorbent or substrate which can be coated with a
barrier material which dissolves in the presence of water.
28. The peracid forming composition can be provided in the form of
granules or particles which include both peracid precursor and
peroxygen source together in the granules or particles. A binder
can be used for holding the peracid precursor and peroxygen source
together in the granules or particles. It should be understood that
the phrase "composite structure" indicates that at least a portion
of the structure includes, in combination, the acid precursor and
peroxygen source. That is, the composite structure includes the
acid precursor and the peroxygen source adhered together. The
composite structure can be used with or without a permeable
container. When it is desirable to treat a wet surface which
requires sanitizing, disinfecting, and/or bleaching, the composite
structure can be applied by broadcasting evenly thereto. It is
expected that this technique may be advantageous when treating
large, wet and rough surfaces. Alternatively, the composite
structure can be measured out and added to a container of water for
generating a volume of sanitizer solution. The composite structure
can additionally include a chemical heater and/or an acid
catalyst
29. Peracid Precursor
30. The peracid precursor and the peroxygen source are reactive, in
the presence of water, to provide an aqueous peracid sanitizer
solution. The peracid precursor preferably remains in solid form at
temperatures up to about 40.degree. C. so that under conditions
often encountered during transportation and storage, the peracid
precursor will remain a solid and will resist reacting with the
peroxygen source until a fluid such as water is introduced.
Furthermore, the peracid precursor should be one which, when
reacted with the peroxygen source, provides a peracid which is
soluble in water. Because the peracid precursor and the peroxygen
source can be provided together within a permeable container or
together in a composite structure, it is desirable that they do not
react together until a fluid such as water is introduced.
31. The peracid precursor is preferably an organic acid. Preferred
peracid precursors are compounds containing at least one acyl group
which is susceptible to perhydrolysis. Suitable peracid precursors
are those of the N-acyl, or O-acyl compound type containing an acyl
radical, R--CO-- wherein R is an aliphatic group having from 5 to
18 carbon atoms, or an alkylaryl of about 11 to 24 carbon atoms,
with 5 to about 18 carbon atoms in the alkyl chain. If the radicals
are aliphatic, they preferably contain 5 to 18 carbon atoms and
most preferably 5 to 12 carbon atoms.
32. Preferred peracid precursors are those which can be provided in
a solid form under conditions normally encountered during storage
of the peracid forming composition, exhibit good water solubility
properties, and react quickly with a peroxygen source in the
presence of water, and are relatively inexpensive. Preferred
peracid precursors include carboxylic acid anhydrides and
carboxylic halides. Preferred carboxylic acid anhydrides include
maleic acid anhydride, succinic acid anhydride, and glutaric acid
anhydride.
33. The peracid precursor can be provided in either a solid form or
a liquid form. It should be understood that reference to "solid"
and "liquid" refers to the state of the peracid precursor under
temperature conditions normally encountered during storage of the
peracid forming composition. In general, solid peracid precursors
are those which remain in a solid state at temperatures up to about
40.degree. C. The peracid precursor can be provided in a solid form
by techniques similar to those used in the laundry detergent
industry. For example, the peracid precursor can be provided in
solid form by spray drying liquid slurries, and by granulation
techniques using binders such as synthetic or natural polymers or
derivatives where blending with binders is followed by extrusion or
other techniques. A liquid peracid precursor can be modified so
that it is provided in a solid form by adsorbing the acid precursor
onto an absorbent or substrate. For example, the peracid precursor
can be absorbed into the pores of a powder or other substrate.
Preferred substrates which can absorb acid precursor include sodium
aluminonsilicates, precipitated silicas, fumed silicas, and
diatomaceous earths. A preferred diatomaceous earth material is
available under the name Celite. In addition, liquid peracid
precursor can be provided in a liquid form and physically isolated
from the other components of the peracid forming composition. For
example, the liquid peracid precursor can be contained in an
envelope which, when physically ruptured, releases the peracid
precursor.
34. Peracid precursors which can be used according to the invention
are those which are provided in the solid form, those which are
provided in a liquid form but which can be modified into a solid
form for use according to the invention, or those which are
provided in a liquid form and can be used in a liquid form
according to the invention. Exemplary peracid precursors include
acetic anhydride, propionic anhydride, butyric anhydride,
isobutyric anhydride, valeric anhydride, methylbutyric anhydride,
trimethylacetic anhydride, hexanoic anhydride, heptanoic anhydride,
octanoic anhydride, nonanoic anhydride, undecanoic anhydride,
decanoic anhydride, lauric anhydride, palmitic anhydride, stearic
anhydride, docosanoic anhydride, crotonic anhydride, methylacrylic
anhydride, oleic anhydride, linoleic anhydride, chloroacetic
anhydride, iodoacetic anhydride, dichloroacetic anhydride,
trifluoroacetic anhydride, chlorodifluoroacetic anhydride,
trichloroacetic anhydride, pentafluoropropionic anhydride,
heptafluorobutyric anhydride, succinic anhydride, methylsuccinic
anhydride, dimethylsuccinic anhydride, itaconic anhydride,
2-dodecen-1-ylsuccinic anhydride, cis 1,2,3,6-tetrahydrophthal- ic
anhydride, norbornene dicarboxylic anhydride, maleic anhydride,
glutaric anhydride, diglycolic anhydride, diethylenetriamine
pentaacetic dianhydride, citric anhydride, tetrahydrophthalic
anhydride, citraconic anhydride, acetyl chloride, chloroacetyl
chloride, trichloroacetyl chloride, propionyl chloride, heptanoyl
chloride, octanoyl chloride, nonanoyl chloride, decanoyl chloride,
undecanoyl chloride, lauroyl chloride, ethyl chloroformate,
ethylene carbonate, propylene carbonate, benzoic anhydride, isatoic
anhydride, phthalic anhydride, and mixtures thereof.
35. Certain peracid precursors which are provided in a liquid form
at a temperature of less than about 40.degree. C. can be modified
so they can be used as solids. One technique for modifying liquid
peracid precursors includes absorbing the liquid peracid precursor
into a powder absorbent material. Preferred absorbent materials
include precipitated silicas, fumed silicas, aluminosilicates, and
diatomaceous earth. The modified liquid peracid precursor can then
be dry blended with the remaining components of the peracid forming
composition.
36. Modified liquid peracid precursors may exhibit a relatively
high vapor pressure. As a result, peracid precursor vapor may
contact the peroxygen source and result in peracid formation. This
type of reaction may result in a decreased effectiveness of the
peracid forming composition over an extended period of time. In
order to increase the shelf life of the peracid forming
composition, it may be desirable to coat the modified liquid
peracid precursor with a coating that provides a gas or moisture
barrier. The modified liquid peracid precursor and/or the peroxygen
source can be coated or encapsulated using conventional technology
generally known in the coating and encapsulating art. In general,
the coating and/or encapsulating can be accomplished in a fluidized
bed. Furthermore, it should be appreciated that both the peracid
precursor and the peroxygen source can be encapsulated.
37. The peracid precursor is preferably provided in an amount which
will provide a desired level of peracid in the peracid sanitizer
for achieving a desired level of sanitizing, disinfecting, and/or
bleaching when combined with peroxygen source and water. In
general, it is expected that the peracid precursor will be provided
in an amount of between about 0.1 wt. % and about 80 wt. % based on
the weight of the peracid forming composition. Preferably, the
peracid precursor is provided in an amount of between about 2 wt. %
and about 30 wt. %, and more preferably between about 5 wt. % and
about 20 wt. %.
38. Peroxygen Source
39. The peroxygen source reacts with the peracid precursor to
provide the peracid sanitizer solution. Preferably, the peroxygen
source does not react with the peracid precursor until it is
desirable for the components to react together. It is generally
desirable for the peroxygen source and the peracid precursor to
react together when water is introduced. In addition, the peroxygen
source is preferably one which will react with the peracid
precursor to provide a peracid reaction product which is soluble in
water. The peroxygen source can include inorganic persalts such as
sodium perborte, sodium percarbonate, calcium peroxide, sodium
peroxide, sodium persulfate, perhydrate of urea, and mixtures
thereof. Preferred peroxygen sources include sodium perborate and
sodium percarbonate. The sodium perborate component is preferably a
monohydrate.
40. The peroxygen source is preferably provided in an amount which
will provide a desired level of peracid in the peracid sanitizer
for achieving a desired level of sanitizing, disinfecting, and/or
bleaching when combined with acid precursor and water. In general,
it is expected that the peroxygen source will be provided in an
amount of between about 0.1 wt. % and about 80 wt. % based on the
weight of the peracid forming composition. Preferably, the
peroxygen source is provided in an amount of between about 2 wt. %
and about 30 wt. %, and more preferably between about 5 wt. % and
about 20 wt. %.
41. Chemical Heater
42. The chemical heater is a component which provides localized
heating for accelerating the reaction between peracid precursor and
peroxygen source. In general localized heating refers to heating
within the container when a container is used. In the case where a
container is not used, for example, when the peracid forming
composition is in the form of a composite structure which can be
applied to a wetted surface, the localized heating refers to the
area in sufficient proximity to the acid precursor and the
peroxygen source to accelerate the reaction to form peracid
sanitizer solution. In the case of providing a composite structure
on a wetted surface, the area in sufficient proximity is generally
the puddle or droplets of water in which the composite structure is
provided. Applicants have found that by providing localized
heating, the rate of peracid formation increases. This is
demonstrated by example 1.
43. When the chemical heater is contacted with water, it hydrates
and generates heat. As water contacts the chemical heater, the
chemical heater generates heat which in turn increases the rate of
peracid formation. In general, it is expected that the chemical
heater, when present, should be present in an amount sufficient to
generate at least about a 5.degree. C. increase in the local
temperature. It is expected that the benefit of localized heating
will not be very great unless the local temperature is increased by
at least about 5.degree. C. Preferably, the local temperature will
increase between about 5.degree. C. and about 25.degree. C. It
should be appreciated that a higher local temperature increase can
be provided at the expense of decreasing the concentration of the
peracid precursor, peroxygen source, or acid catalyst for a given
volume of peracid forming composition.
44. A preferred chemical heater can be referred to as a heat
generating desiccant. Preferred chemical heaters include zeolites,
calcium sulfate, calcium oxide, calcium peroxide, magnesium
sulfate, magnesium chloride, magnesium bromide, phosphorous
pentoxide, sodium acetate, ferric chloride, ferric bromide,
aluminum chloride, and aluminum bromide, aluminum iodide, aluminum
sulfate, aluminum iodide, calcium bromide, calcium chloride,
ferrous iodide, ferrous sulfate, magnesium iodide, pyrophosphoric
acid, zinc chloride, zinc sulfate, and mixtures thereof.
45. Although water is a preferred trigger for causing the chemical
heater to generate heat, other triggers can be used. The chemical
heater can generate heat by hydration, hydrolysis, acid-base
neutralization, and the like. An exemplary acid-base neutralization
includes the combination of sodium hydroxide and citrus acid.
Additional acids include those listed below as acid catalysts.
Bases which can be used with acid include potassium hydroxide,
sodium hydroxide, calcium oxide, aluminum oxide, sodium carbonate
and mixtures thereof.
46. It is generally desirable that the chemical heater is one which
will not cause too great of an increase in the pH or provide such a
violent rate of heat generation that causes dispersion of the
peracid composition or rupture of the permeable container. For
example, sodium hydroxide and phosphorous pentoxide
(P.sub.2O.sub.5) can be considered to be too caustic if used in too
great an amount. It should be understood, however, that these
components can be used if the pH is controlled so that the aqueous
peracid sanitizer solution is provided with a pH of less than about
8, and more preferably less than about 7. In a preferred embodiment
of the invention, the aqueous peracid sanitizer solution is
provided with a pH of between about 2 and about 4 when corrosion is
not a concern. When corrosion is a concern, it is generally
desirable to buffer the peracid sanitizer solution near a pH of
about 7.
47. The amount of chemical heater provided in the peracid forming
composition is determined by the desired amount of local
temperature increase and depends on the selected chemical heater.
Certain chemical heaters provide greater generation of heat than
others. In general, it is expected that when the chemical heater is
incorporated into the peracid forming composition, it will be used
in an amount up to about 80 wt. % based on the weight of the
peracid forming composition. While a greater amount of chemical
heater can be used, it is expected that increasing the amount of
chemical heater much beyond 80 wt. % will result in a reduction in
the concentration of acid precursor and peroxygen source.
Preferably, the chemical heater is provided in an amount of between
about 10 wt. % and about 60 wt. %, and more preferably between
about 20 wt. % and about 40 wt. %.
48. Acid Catalyst
49. The acid catalyst can be provided to accelerate the rate of
peracid formation and/or to help maintain the pH of the resulting
aqueous peracid sanitizer solution in the range of below about 8,
and more preferably below about 7. The acid catalyst is preferably
one which remains a solid prior to the peracid forming reaction.
The acid catalyst can be a liquid which has been modified to a
solid form. In addition, the acid catalyst is preferably a strong
acid exhibiting a pKa of less than about 3 and more preferably less
than about 1. Of course, it should be appreciated that the system
of the invention need not include an acid catalyst. Exemplary acid
catalysts which can be used according to the invention include
sulfamic acid, citric acid, sodium monohydrogen sulfate, hemi
sodium phosphate, aluminum trichloride, iron trichloride, and
mixtures thereof.
50. When the acid catalyst is used, it is preferably used in an
amount which provides the desired rate of peracid formation and/or
provides the peracid sanitizer with the desired pH. It should be
appreciated that the amount of acid catalyst depends on the
particular acid catalyst selected. In general, the acid catalyst
can be provided in an amount of up to about 20 wt. % based on the
weight of the peracid forming composition. Preferably, the acid
catalyst is provided in an amount of between about 2 wt. % and
about 10 wt. %.
51. Viscosity Modifier
52. The peracid forming composition can include a viscosity
modifier which has a tendency to increase the viscosity in the
localized area created by the reaction of peracid precursor and
peroxygen source. In the case where the peracid precursor and
peroxygen source react within a permeable container, the interior
region of the permeable container can generally be referred to as
the localized area. By increasing the viscosity in the localized
area, the movement of peracid precursor and/or peroxygen source out
of the permeable container is slowed. This results in an increased
residence time of the peracid precursor and peroxygen source within
the permeable container which provides a greater reaction rate. A
preferred viscosity modifier is one which remains solid under
normal storage conditions (i.e., at a temperature of less than
about 40.degree. C.), remains inert in an oxidizing environment,
and exhibits a neutral or acidic pH when dispersed in water.
53. The viscosity modifier can include natural and synthetic
polymers. Preferred viscosity modifiers include xanthun gum, guar
gum, acrylic polymers, polyoxyethylene, and mixtures thereof. The
viscosity modifier is preferably added in an amount which provides
a viscosity within the localized area of between about 300
centipoise and about 2,000 centipoise. The viscosity modifier can
be added in an amount of up to about 5 wt %. Preferably, the
viscosity modifier is provided in an amount of between about 0.5 wt
% and about 2 wt %.
54. Binder
55. The composite structure includes both peracid precursor and
peroxygen source bound together. In order to bind the peracid
precursor and peroxygen source together, a binder can be used. The
binder can be the peracid precursor component. Exemplary peracid
precursors which can function as binders include glutaric anhydride
and maleic anhydride. The binder can additionally include other
components such as alcohol ethoxylates and homopolymers and/or
copolymers of ethylene oxide and/or propylene oxide. Preferred
alcohol ethoxylates include C.sub.12-C.sub.15 is fatty alcohol
ethoxylates and C.sub.14-C.sub.15 fatty alcohol ethoxylates with 5
moles of ethoxylation. In addition, preferred ethylene oxide
polymers include polyethylene glycol of molecular weight of about
8,000 and polyethylene glycol methyl ether of molecular weight of
about 750.
56. The composite structure is preferably prepared by a method
which avoids or minimizes the reaction of peracid precursor and
peroxygen source. In general, this method preferably takes place in
the general absence of water. The peracid precursor and peroxygen
source can be mixed with molten binder. The resulting composition
can be cooled to provide a solid, then crushed and sieved to
provide an composite composition. U.S. Pat. No. 5,670,684, which is
incorporated herein by reference, describes a process for utilizing
a hot melt binder. This process can be used to provide a composite
composition according to the present invention.
57. Moisture Barriers
58. Moisture barriers can be provided coating the composite
structure or a component of the composition to reduce the
penetration of the solvent vapor into the component. In particular,
it is desirable to restrict the penetration of water vapor from
contacting the peracid precursor and/or peroxygen source.
Accordingly, the peracid precursor, peroxygen source, or composite
structure can be coated with a moisture barrier. Exemplary
materials which can be provided as moisture barriers include
monoethanol amides of stearic acid, magnesium stearates, calcium
stearates, polyethylene glycols, alcohol ethoxylates, ethylene
bis-stearamides, mono and dihexadecyl phosphate esters, and
mixtures thereof. Preferred polyethylene glycols have a molecular
weight of about 20,000 to about 200,000. Particularly preferred
polyethylene glycols have molecular weights of about 50,000 to
100,000. Preferred alcohol ethoxylates include C.sub.14-C.sub.15
fatty alcohol ethoxylates with five moles of ethoxylation and
C.sub.12-C.sub.15 fatty alcohol ethoxylates with 12 moles of
ethoxylation.
59. Permeable Container
60. The permeable container is provided to contain the peracid
forming composition prior to introduction of the system into an
aqueous solution. Accordingly, the permeable container is permeable
to water. That is, water can flow into the permeable container and
peracid solution can flow out of the permeable container.
61. The permeable container can be any material which holds the
peracid forming composition together and which is permeable to
water and peracid solution. Preferred materials which can be used
to form the permeable container include cellulosic material such as
paper or tissue. The material forming the container can be
characterized as a membrane. The permeable container can be
constructed from cellulosic membranes such as those available under
the name Precision Wipe from Kimberly Clark, or a two-phase
heat-sealed tissue such as grade 1234T from Dexter Corp. In
addition, the permeable membrane can be manufactured from a soluble
membrane, such as, polyvinyl alcohol, which will dissolve in
water.
62. Now referring to FIG. 1, a system for forming and releasing an
aqueous peracid sanitizer solution is indicated at reference
numeral 10. The system 10 includes a container 12 and a peracid
forming composition 14 provided within the container 12. The
container 12 is permeable to the passage of water and an aqueous
peracid sanitizer solution. Preferably, the container 12 is
provided within an envelope 16 which is relatively moisture
impermeable. Accordingly, the envelope 16 prevents humidity from
entering into the peracid forming composition 14. When the envelope
16 is opened, the container 12 can be removed and placed in water.
A line 17, such as a string, can be provided to assist removing the
spent system from the sanitizing solution.
63. The combination of the container 12 and the peracid forming
composition 14 can be referred to as a package 18. In general, the
size of the package 18 can be adjusted for providing the desired
size or strength of sanitizing solution. For example, the package
18 can be sized to provide one gallon of sanitizing solution.
Accordingly, any multiple of one gallon of sanitizing solution can
be provided by incorporating the corresponding number of packages.
For example, five gallons of sanitizing solution can be prepared by
introducing five packages into a five-gallon container of water.
Because it is expected that the system of the invention will be
advantageously used by household consumers, each package can
advantageously provide a small amount of sanitizing solution.
64. It is an advantage of the invention that the peracid forming
composition is more stable than commercially available aqueous
peracid sanitizer solutions. In addition, the peracid forming
composition of the invention is easy to use and provides a
reduction in packaging size and shipping cost compared with
commercially available aqueous peracid sanitizer solutions.
Furthermore, the invention provides for the enhanced rate and yield
of peracid formed from the peracid forming composition.
65. Now referring to FIG. 2, an alternative system for forming and
releasing an aqueous peracid sanitizer solution is indicated
reference 50. The article 50 includes a container 52, a first
peracid forming component 54, and a second peracid forming
component 56 which is provided within a rupturable container 58.
The first peracid forming component 54 and the second peracid
forming component 56, when contacted, generate peracid. The
rupturable container 58 is provided to keep the components 54 and
56 from contacting each other. Accordingly, just before the article
50 is placed in water, the rupturable container 58 can be ruptured
thereby releasing the second peracid forming component 56.
Alternatively, the rupturable container 58 can be allowed to
degrade thereby releasing the second peracid forming component 56.
In most situations, it is expected that the second peracid forming
component 56 within the rupturable container 58 is a peracid
precursor, especially, a liquid peracid precursor.
66. Now referring to FIG. 3, a composite structure is shown at
reference 100. The composite structure 100 includes a first peracid
forming component 102 and a second peracid forming component 104
held together by a binder 106. It should be appreciated that the
binder 106 and one of the peracid forming components 102 or 104 can
actually be the same material. A protective coating 110 can be
provided enclosing the composite structure. Preferably, the
protective coating 110 preferably acts as a moisture barrier to
prevent humidity from causing the peracid forming components to
react. It should be appreciated that the protective coating can be
omitted. If a protective coating is not provided, it is desirable
to limit the ability of moisture to enter the composite structure
by providing, for example, an envelope or moisture barrier such as
provided in FIG. 1. While envelope or coating type moisture
barriers are preferred, other types of containers can be used to
limit or reduce moisture from contacting the composition.
67. Now referring to FIG. 4, an alternative embodiment of a
composite structure according to the invention is indicated at
reference 120. The composite structure 120 includes a first peracid
forming component 122, a second peracid forming component 124, and
a binder 126 for holding the first peracid forming component 122
and the second peracid forming component 124 together. In addition,
a protective coating 128 can be provided as a moisture barrier. It
should be understood that the protective coating 128 is
optional.
68. The system and the composite structure can be used for
sanitizing, disinfecting, and/or bleaching different types of
surfaces. The system is preferably used when it is desirable to
generate a quantity of sanitizer solution. This quantity of
sanitizer solution has particular use for hard surface
disinfection, potable water disinfection, food surface sanitization
including fruit, vegetables and meat, medical instrument
sterilization, and kitchen (third sink) sanitizer. The composite
structure, when used without a permeable container, can preferably
be used to generate sanitizer solution at a particular location.
For example, the composite structure can be used as a biohazard
cleanup powder, a carpet sanitizer powder, floor powder for a
walk-in freezer, and ostomy deodorizer. For example, it may be
easier to clean certain types of surfaces by generating the
sanitizer solution on that surface, rather than trying to apply the
sanitizer solution to the surface.
EXAMPLE 1
69. Four test compositions identified as A-D were prepared and
tested. The components of each composition include glutaric
anhydride, sodium perborate, sulfamic acid, and magnesium sulfate.
The parts by weight of each component for each test composition is
identified in Table 1.
1TABLE 1 Glutaric NaBO.sub.3 Sulfamic Permeable Test Anhydride
H.sub.2O Acid MgSO.sub.4 Container Grams A 2.5 2.0 4.0 6.0 No 14.5
B 2.5 2.0 4.0 6.0 Yes 14.5 C 2.5 2.0 4.0 0.0 Yes 8.5 D 2.5 2.0 4.0
12.0 Yes 20.5
70. Test composition A is a control where the composition was added
directly to 1000 ml of deionized water without the use of a
permeable container. Test compositions B-D were enclosed in paper
wipe available as Precision Wipe from Kimberly-Clark. The permeable
containers were prepared by folding the paper wipe, taping and
stapling. Each permeable container containing a test composition
was immersed in 1000 ml of deionized water. The permeable
containers were provided having a dimension of about 4.5 inches by
8.25 inches.
71. For each test, a 10.0 gram aliquot of solution was removed at
time intervals of 5, 15, and 30 minutes and diluted into 90 ml of
deionized water, which was further diluted by a factor of 5 to
achieve total dilution of 50.times.. The 50.times. solutions were
assayed for peracid using the method described below. The results
are reported in Table 2.
2 TABLE 2 Drops of ppm Drops of ppm Drops of ppm Test MgSO.sub.4
titrant POAA titrant POAA titrant POAA A (no permeable 6.0 2 19 2
19 2 19 container) B 6.0 6 121 9 197 11 248 C 0.0 4 70 6 121 7 146
D 12.0 8 172 10 1050 12 274
72. The data in Table 2 is graphed in FIG. 5. The data shows the
benefit of using a permeable container, and a chemical heater, for
increasing the rate of aqueous peracid sanitizer solution
formation. The peracid level was determined by an iodometric
titration method. 20 g of sample was added to a plastic vial with a
micro stir bar and with rapid stirring. Then 5 drops of reagent
(10% KI) was added, followed by 5 drops of (59% H.sub.3PO.sub.4),
followed by 5 drops of indicator (2% starch indicator). The three
reagents above were added within 30 seconds with vigorous stirring.
The titration with 0.08% Na.sub.2S.sub.2O.sub.3 solution followed
immediately, yielding the number of drops needed to make the
iodine-starch blue color disappear. Calibration was done with a
known peracetic solution (KX6091, 11.4% POAA or peroxyacetic acid),
which yielded the calibration curve:
73. Equivalent POAA in ppm=0.508.times.(drops of 0.08%
Na2S2O3)+1.275
74. To demonstrate the effectiveness of MgSO.sub.4 as a chemical
heater, the following two formulas were packaged in permeable
containers and immersed in 1.0 L of deionized water. The
temperature profiles were recorded using a low heat capacity
thermistor embedded in the body of the powder within the sachets.
The results are reported in FIG. 6. The composition and the
temperature differential is reported in Table 3.
3TABLE 3 Succinic NaBO.sub.3 Sa- Test Anhydride H.sub.2O Sulfamic
MgSO.sub.4 chet Grams .DELTA.T.degree.C E 2.5 2.0 4.0 6.0 Yes 14.5
7 F 2.5 2.0 4.0 12.0 Yes 20.5 26
EXAMPLE 2
75. This example demonstrates the use of an active ingredient as a
binder for forming a composite structure.
4 Glutaric anhydride 10 g Mg SO.sub.4 (granular, anhydrous) 12 g
Sodium perborate monohydrate 5 g
76. Glutaric anhydride was added molten (57.degree. C.) to the dry
blend of the remaining two components. After cooling to room
temperature, the fused composite was crushed and sieved to provide
a size of between 16 and 10 mesh (US Standard Testing Sieve,
particle size range is between 1.18-2.00 mm).
77. The following procedure was used to evaluate the localized
reaction. To simulate application of the particles on wet, porous
surfaces such as soil or soiled floor, we applied the composite
structure by broadcasting onto a multi-well tray, the wells being
partially filled with water, and let stand for a period of time.
The wells were emptied and rinsed and the pooled solution was
titrated for peracid. For control, the same quantity of the
formulation in a powder blend was broadcast and assayed in the same
manner.
78. For 110 mg samples broadcast over 96 wells, each having about
0.17 g of water, and with 1000 ml total pool, the assay results
were:
79. ppm POAA
80. Composite structure 14.5
81. Powder blend 4.8
EXAMPLE 3
82. This example demonstrates that liquid peracid precursors can be
incorporated into powder absorbent materials such as precipitated
silicas, fumed silicas, aluminosilicates, and diatomaceous earth.
Preferably, the liquid precursor is incorporated into the powder
absorbent materials prior to blending with the remaining components
of the peracid forming composition.
83. 2.48 g of a (2:1 w/w) mixture of acetic anhydride and acetic
acid was absorbed onto 0.82 g precipitated silica (Sipernet 50 from
Degussa), which was blended with 2.0 g of Sodium perborate
monohydrate, 4.0 g of sulfamic acid and 6.0 g of magnesium sulfate.
The total 15.3 g of this formulation was enclosed in a permeable
container made of nonwoven cellulosic membrane (Precision Wipe from
Kimberly Clark). The permeable container containing peracid forming
composition was immersed in 1,000 ml of DI water at ambient
temperature. 83 ppm of POAA was found after 10 minutes of dipping
time, and 180 ppm was found after 30 minutes.
84. The above specification, examples and data provide a complete
description of the manufacture and use of the composition and
article of the invention. 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.
* * * * *