Note: Descriptions are shown in the official language in which they were submitted.
21 n~9
)92/16309 PCT/DK92/00096
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A process for the cleaning and protection, including
corrosion protection, preservation and disinfection, of
surfaces, and an agent for use in the process
_ _ _ _ _ _ _ _ _ :
The present invention relates to a process of the kind
stated in the introductory portion of claim 1 for the
cleaning and protection, including corrosion protection,
preservation and disinfection of surfaces, e.g. in under-
takings and institutions in the food and pharmaceuticalindustries and in hospitals. The process according to the
invention is directed at both production rooms and
furniture and equipment. The invention also relates to an
agent for use when carrying out the process.
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For daily, current and periodic cleaning of production
rooms, including machinery, equipment and furniture, e.g.
in the food and pharmaceutical industries, use is mainly
made of foam cleaning followed by disinfection. By the
foam cleaning the surfaces to be cleaned are typically
first coarsely washed with hot or cold water under
pressure (typically 20-120 bar) in view of removing all
loose and water soluble dirt. Then the surfaces are foamed -
with a cleaning agent having a loosening effect on dirt -
debris, typically in 5-15 min, and which may basic,
neutral or acidic depending on the dominating type of
dirt. The surfaces are then cleaned with hot or cold water
under pressure (typically 20-120 bar) in order to remove
debris of dirt and cleaning agent, and finally the cleaned
surfaces are disinfected with hot water (above 80C) or
with chemical disinfectants (hypochlorites, peroxides,
peracetic acid, quaternary ammonium compounds or the
like). This disinfection may optionally be succeeded by a
surface treatment with liquid paraffin. All these process
steps are usually performed manually by cleaning staff,
but the disinfection process may be performed automatic-
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WO92t16309 PCT/DK92/00096
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ally by means of atomizers.
Such processes for required daily, current and periodicmaintenance of the hygiene level are, however, very time-
consuming, costly and environmentally unfriendly. Further-
more, they are non-reproducible and often also inadequate
in view of achieving a hygiene level fulfilling the high
demands today placed on the hygiene of surfaces, in
particular within the food, beverages and tobacco
industries, in hospitals and the like places. In such
places any contamination constitutes a risk of existence
and growth of bacteria, ~unsi and oth2r microorganisms,
whose presence is undesired, i.a. because of the risk of
contamination of raw and finished products.
- 15
The cleaning technology used today for maintaining the
desired hygiene level of surfaces in e.g. food processing
undertakings and the like places is - irrespective of the
selected cleaning type - attached with very essential
disadvantages and costs, among which in particular the
following should be mentioned:
l. The technology is time-consuming because the daily
cleaning and disinfection often takes 5-8 hours, in
which period the production apparatus cannot be used.
2. The technology is costly which goes for both direct
costs (for paying cleaning staff and for energy and
water consumpt~on) and indirect costs (in the form of
environmental impact caused by the cleaning).
: . .
3. The technology is environmentally unfriendly both as ~-
regards working environment and surrounding environ-
ment because large amounts of deleterious chemicals
are used and because water and energy consumption are ~ -
large.
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- ~92tl6309 ~ 9 PCT/DK92/00096
4. Finally, the traditional cleaning technology, such as
foam cleaning, is insufficient in view of ensuring
clean production rooms, which entails a very
substantial risk of health hazardous and low
durability products.
.:
Thus there is a very large need for new processes with
which it is possible quickly, uniformly and in a
completely reproducible way to ensure that the daily
cleaning results in clean and germ-free production
conditions at a minimum of costs.
.,.".
By the process according to the invention there is
obtained a surprisingly simple, fast, cheap and reliable
process whereby this object can be fulfilled.
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More specifically, the invention relates to a process for
the protection (including corrosion protection, preserva-
tion and disinfection) and cleaning of all surfacessubjected to daily, periodical or current cleaning and
which between treatment and cleaning are or may be exposed
to water and aqueous solutions, such as all external and - -
internal surfaces in the food industry, wet-room surfaces,
transport materiél, furniture, equipment and the like. The
process according to the invention is thus usable for all
surfaces which are cleaned daily, currently or
periodically, and where the surfaces between treatment
and cleaning are not exposed to basic solutions (pH 9)
30 or solutions containing solvents which without the -
presence of base are capable of dissolving the applied -
plastic~film. Thus, the process according the invention is
characterized in that the cleaned surfaces are coated with
a substance forming a dense, aseptic and water insoluble
plastic film on which all kinds of dirt can settle and
which subsequently is removable by washing with water
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W092/16309 PCT/DK92/00096
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adjusted to pH 29 or with any other liquid having dis-
solving effect, whereby also the dust settled on the film
is removed.
The invention is based on the recognition that if all
surfaces in e.g. production rooms, including surfaces of
equipment and furniture, are completely clean and prior to
the start of production have been applied with a substance
which is chemically inert and non-toxic and which forms a
dense, water insoluble, pro~ective and serm-free film on
the surfaces, which film is easily removable by means of
water having a pH-value of 9 or more or other aqueous
solutions capable of dissolving the film, then the
surfaces will be aseptic at the start of production.
Contaminations of any kind which are settled on the
surfaces can then be removed after the production merely
by washing with water ad~usted to pH 29 or with any other
aqueous solution capable of dissolving the film. The film-
forming substance may be applied automatically by means of
any kind of suitable atomizer, while the washing with
pH-adjusted water is preferably performed manually. AlSo
the pH-adjusted water can, however, be applied
automatically, whereafter washing is with clean water.
Hereby the cleaning will be extremely simplified in
comparison with the known technique, and the production
surfaces will after cleaning be aseptic and germ-free.
The cleaning of the surfaces with pH-adjusted water is
performed solely by washing irrespective of the contamina-
tion type, and there are no special demands on pressure,temperature or other parameters. However, the pH-value of
the water must be adjusted to at least 9 or else the water
must be added with chemicals capable of dissolving the
film. Hereby the film and the dirt thereon loses its
adhesiveness to the surface which is thereafter completely
clean. Then a new water insoluble, dense film is applied
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- ~92/16309 ~ 9 PCT/DK92/00096
-- 5
by means of an automatic atomizer or by any other
application method.
In this way it is made possible to perform the daily,
5 current or periodic cleaning very quickly without using .-
anything else but water and a non-toxic chemical, without
using pressure cleaning equipment, without unfortunate
impacts on users, surfaces and environment, and with
simultaneous attainment of clean, aseptic surfaces.
, ..
Danish patent application No. 2894/77 discloses a process
for the protection and cleaning of surfaces exposed to
soiling. The thus known process, however, involves surface
treatment with water soluble agents, and it is consequent-
ly only usable for protection of hydrofobic, oily dirt on
surfaces which moreover not before the cleaning are
influenced by water or aqueous solutions. Contrary hereto,
the process according to the invention involves a surface
treatment for the protection of the surface against both
20 hydrofobic and hydrophilic dirt, the surface being applied : -
with a water and oil insoluble film. Therefore the process
according to the invention is usable on surfaces which
between application of the plastic film and cleaning are
exposed to water, which e.g. is so within the food -;
industry.
Also from Japanese public disclosure No. 78/108121 (cf.
Chemical Abstracts vol 93 (1980) No. 27894b) is it known
to coat solid objects with a substance forming a protect-
ive film which after soiling can be dissolved with water,whereby the object is cleaned. Thus the Japanese
specification discloses a process where the object is -
first coated with a polyvinyl alcohol film and thereafter
soiled with vegetable oil. By submerging the soiled
3~ object in water (20 JC) for 7 min the film becomes
removable.
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W092/16309 PCT/DK92/00096
However, the thus ~nown process is not usable for cleaning
surfaces in food processing undertakings or other surfaces
which in between treatment and cleaning are exposed to
water, since polyvinyl alcohol is water soluble. It is not
possible either to use polyvinyl alcohol on surfaces
getting into contact with foodstuffs since polyvinyl
alcohol is not approved for contact with foodstuffs. The
method known from the Japanese disclosure is furthermore
only usable on objects having such restricted size that
they can be submerged or washed for the period required
for dissolving the film.
The surface treatment performed by the process according
to the invention furthermore results in an aseptic film
whereby the treatment causes a disinfection. Besides, the
film used can~be employed in connection with foodstuffs.
These properties appear neither from Danish patent
application No. 2894/77 nor from Japanese public
disclosure No. 78/108121.
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The film-forming agent used by the process according to
the invention can be any substance of a mixture of such
substances which by application to cleaned surfaces form a
-dense film which is not dissolved by water at pH-values
below 9, which are dissolved by water at pH-values of 9 or
more or other aqueous solutions, and which can be
approved in connection with food.
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A number of substances are known having this desirable
combination of properties. The agent most preferred for
use in the process according to the invention is a plastic
polymer, e.g. in the form of a combination of maleate
~ resin and polyethylene. ~ -
35
Plastic polymers having the above properties are moreover
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~92/16309 ` PCT/DK92/00096
either pure polymer dispersions like e.g. a combination of
acrylates and polyethylene or the above combination of
polyethylenes and montan wax. The reason why plastic
polymers after dryin~ (film-formation) are removable with
base is either (l) that the plastic polymer in its
chemical composition contains free acid groups which by
neutralization with base entails reduced adhesiveness to
surfaces and/or dissolution of plastic structures, or (2)
that the plastic polymer is water soluble because of the
base content (e.g. ammonia), which during drying and film
formation evaporates, since the plastic polymer by react-
ion with base subsequently can be made water soluble
again. In the latter case the aqueous solution of the
plastic polymer is basic because of the ammonia content,
but neutral or acidic following film-formation because of
evaporation of ammonia. This pH-shift can, by addition of
an acid/base colour-indicator, such as e.g. phenol-
phthalein (colourless at pH <8.2-9.8, and red at pH >8.2-
9.8) to the plastic polymer solution, if pH is more than
9, be used for controlling whether the application is
correct on all surfaces (the applied solution being bright
red), whether a plastic film is present on all surfaces
(the film turning red by contact with base) and whether
all surfaces are cleaned correctly (the film turning red
by cleaning with a basic solution (pH >9)). Thus it is
possible in a simple way to control all steps in the
cleaning, including controlling the presence of plastic
film at all times, also during the production.
The above combination of polyethylene and maleate resin is
preferred because it is extremely suited for the purpose:
Thus it has been approved in connection with foodstuffs,
and it has high adhesiveness and large anti-release
effect. Furthermore it is completely waterproof and has a
3~ high dirt-repellent capability, and is also extremely wear
resistant. The toxicity is negligent, and the agent
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W092/16309 PCT/DK92/00096
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contains no phosphate, is not marked hazardous and is
biodegradable.
The polymers mentioned in Danish patent application No.
2894/77, such as cellulose, starch, polyethylene glycols
and polyvinyl alcohol, only serve as thickeners in view of
obtaining a certain viscosity. All these polymers are
water soluble and consequently cannot be compared with the
water insoluble plastic polymers used by the process
according to the invention.
Since the process according to the invention does not
employ strong chemicals, including disinfectants, there is
no risk of build-up of resistant bacteria chemically.
~he film-forming agent can be applied automatically in
closed rooms by means or aerosol nozzles. Advantageously
use can be made of an atomizer of a type the nozzles of
which are capable of atomizing with a particle size of
less than 3 ,um, whereby it is achieved that the particles
can be distributed with the ordinary room air. Hereby it
e.g. is possible to shroud a room of 800 m3 in a
completely dense fog in a few minutes using less than 10
litres of liquid. Even complicated production equipment
with surfaces which are either difficult to access or
hidden can be treated effectively in this way. An atomizer
of this type is today commonly used for e.g. air-
moistening and room-disinfection.
lt is also possible to apply the film-forming agent
manually, e.g. by means of form equipment or sprayer.
The process according to the invention emplo~s pH-adjusted
water for the cleaning. The required pH-adjustment to pH
9 can be performed with any chemical providing alkaline
reaction in the pH-area ~9. Chemicals, such as e.g. sodium
)92/16309 ~1 ~ PCT/DK92/00096
hydroxide, potassium hydroxide and metasilicates, are thus
usable.
The advantages of the process according to the invention
are evident, since hereby it becomes possible to perform
cleaning and maintenance of production rooms and other ~ -
surfaces
l) Without use of aggressive chemicals.
lO 2) Without use of hot water. ~ -
3) Without use of pressure equipment.
4) With surface protection of belts and the like. ,
S) With corrosion protection of metal surfaces.
6) In a very short time.
lS 7) Independently of dirt occurence and type.
8) Without risk of build-up of resistant bacteria.
. . :
The advantages attached to the process according to the
invention entail considerable reductions as regards both
staff and resources, more specifically:
l) Water savings
2) Energy savings
3) Improved working environment
4) Reduced sewage pollution
S) Personnel reduction
6) Reduced consumption of cleaning chemicals.
7) No use of disinfectants.
8) Easier cleaning and reduced cleaning time.
9) Improved hygiene (aseptic surfaces).
lO) At the most two cleaning or maintenance agents.
The process according to the invention is usable in
combination with all kinds of periodic cleaning of
surfaces, such as foam cleaning, manual cleaning,
circulation cleaning, cleaning of transport equipment, in
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WO92/16309 PCT/D~92/00096
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washing machines, when cleaning containers etc.
The invention is described in more detail by the following
example.
EXAMPLE
.
In a food processing plant within the fishing industry the
process according to the invention was used instead of
traditional cleaning and disinfection, and thereafter it
was evaluated whether on the following day the cleaning
was easier. Also the treated surfaces were examined micro-
biologically.
The surfaces were cleaned with an alkaline (pH >9) clean-
ing agent (2%) after coarse washing with water. Thereafter
a plastic polymer of the preferred type in a 2.5% solution
was applied on all surfaces by means of atomizing equip- -
ment. Because of the indicator added to the polymer
solution it was immediately detectable whether all corners
had been reached, since the solution was red when being
applied. After drying the red colour disappeared. The
cleaning control was performed the next morning.
The hygiene measurements were based on germ count on
sampled specimens, and the hygiene was assessed according
to a point system as follows:
Number of colonies 0-2 3-31 32-lOO >lOO
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Point O 1 2 3
A point value of 2 or more indicates that the cleaning was
35 insufficient. --
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~92/16309 PCT/DK92/00096
In all cases, i.e. at all sampling points, the colony
number, however, was below 1, which~ gives O point. That
is, the cleaning was in all cases most satisfactory.
The later cleaning after intermediate production also
appeared to be much easier. Thus, there was not as much
dirt as usually, and after foaming the coating was much
easier to remove than normally. During the cleaning after
production it was thus possible by means of pH-adjusted
lO water (pH >lO) to establish that the coating had not been :
worn off during the production, since the indicator in the
film had turned red again.
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