U.S. patent application number 10/468669 was filed with the patent office on 2005-04-28 for water-soluble glass as corrosion protector in dishwashing machines.
Invention is credited to Hahn, Karlheinz Ulrich Gerhard.
Application Number | 20050087213 10/468669 |
Document ID | / |
Family ID | 9909254 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050087213 |
Kind Code |
A1 |
Hahn, Karlheinz Ulrich
Gerhard |
April 28, 2005 |
Water-soluble glass as corrosion protector in dishwashing
machines
Abstract
A zinc-containing, water-soluble glass composition comprising
from 41 to 54 mole % of P.sub.2O.sub.5, 10 to 30 mole % of alkali
oxides, up to 5 mole % of SO.sub.3 and up to 25 mole % of ZnO.
Inventors: |
Hahn, Karlheinz Ulrich Gerhard;
(Otterstadt, DE) |
Correspondence
Address: |
Norrison McLaughlin & Marcus
30th Floor
220 East 42nd Street
New York
NY
10017
US
|
Family ID: |
9909254 |
Appl. No.: |
10/468669 |
Filed: |
February 13, 2004 |
PCT Filed: |
February 18, 2002 |
PCT NO: |
PCT/GB02/00684 |
Current U.S.
Class: |
134/25.1 ;
501/45; 501/73 |
Current CPC
Class: |
C03C 4/0064 20130101;
C03C 2218/355 20130101; C03C 3/16 20130101; C11D 3/0073 20130101;
C03C 4/0035 20130101; C11D 3/08 20130101 |
Class at
Publication: |
134/025.1 ;
501/045; 501/073 |
International
Class: |
B08B 009/20; C03C
003/16; C03C 003/062 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2001 |
GB |
0104347.0 |
Claims
1. A zinc-containing, water-soluble glass composition comprising:
from 41 to 54 mole % of P.sub.2O.sub.5, 10 to 30 mole % of alkali
oxides, up to 5 mole % of SO.sub.3 and up to 25 mole % of ZnO.
2. The composition according to claim 1 characterised in that not
more than 40 mole % of the total amount of alkali oxides in the
composition is constituted by one or more members of the group
consisting of Li.sub.2O and Na.sub.2O.
3. The composition according to claim 1 characterised in that the
composition additionally comprises at least one alkaline-earth
oxide with a total amount of alkaline-earth oxides of less than 20
mole %.
4. The composition according to claim 1 characterised in that the
composition additionally comprises at least one oxide of antimony
or arsenic present in the composition in an amount of of less than
5 mole %.
5. The composition according to claim 1 characterised in that the
composition additionally comprises at least one oxide of an element
from the group consisting of silicium, germanium, tin and lead
present in the composition in an amount of with a total amount of
such oxides of less than 10 mole %.
6. The composition according to claim 1 characterised in that the
composition it additionally comprises at least one oxide of an
element selected from the group consisting of silicon, aluminium
and boron present in the composition in an amount of from 0. 1 to
10 mole.
7. The composition according to claim 1 characterised in that the
composition does not comprise more than 0.5 mole-% of oxides of
elements from the group IIIb of the Periodic System of
Elements.
8. The composition according to claim 1 characterised in that the
composition comprises from 41 to 54 mole % of P.sub.2O.sub.5, from
10 to 30 mole % of alkali oxides, up to 5 mole % of SO.sub.3, up to
25 mole % of ZnO, less than 5 mole % alkaline-earth oxides, and
from 0.3 to 3 mole % of oxides of elements selected from the group
consisting of silicon, aluminium and boron.
9. The composition according to claim 1 characterised in that the
composition is present in the form of a transparent shaped
body.
10. The composition according to claim 9 characterised in that the
shaped body is manufactured by continuous glass manufacturing
processes.
11. The composition according to claim 1 any of claims 1 to 8
characterised in that the composition it is present in a comminuted
form.
12. The composition according to claim 11 characterised in that the
composition is manufactured by the breaking of thin glass
plates.
13. The composition according to claim 11 characterised in that the
composition is manufactured by a process which includes a milling
step.
14. The composition according to claim 13, characterised in that
the milled glass has an average particle size of not more than 500
microns.
15. A process for the inhibition of corrosion of glassware in an
automatic dishwashing process which comprises the step of:
contacting said glassware with a zinc-containing, water-soluble
glass composition according to claim 1.
16. A process for the inhibition of corrosion of glassware in an
automatic dishwashing process characterised by: providing a
zinc-containing, water-soluble glass composition according to claim
1 at an appropriate place within an automatic dishwashing machine
wherein the said composition is accessible to the wash liquor
and/or rinse water.
17. A process for the inhibition of corrosion of glassware in an
automatic dishwashing process characterised by: contacting the
glassware, in an automatic dishwashing machine, with wash liquor
and/or rinse water containing an effective amount of a composition
according to claim 1.
18. A process for the inhibition of corrosion of glassware in an
automatic dishwashing process characterised by: providing a
zinc-containing, water-soluble glass composition according to claim
9 at an appropriate place within an automatic dishwashing machine
wherein the said composition is accessible to the wash liquor
and/or rinse water.
19. A process for the inhibition of corrosion of glassware in an
automatic dishwashing process characterised by: contacting the
glassware, in an automatic dishwashing machine, with wash liquor
and/or rinse water containing an effective amount of a composition
according to claim 11.
Description
[0001] The invention is related to a novel zinc-containing,
water-soluble glass composition, the use thereof for inhibition of
corrosion of glassware in an automatic dishwashing process and
related processes.
[0002] Corrosion of glassware in cleaning and/or rinsing cycles of
an automatic dishwashing machine is a well-known problem. It is
believed that corrosion of glassware can be seen as two separate
phenomena. On the one hand, corrosion is obviously caused by the
leakage of minerals from the glass composition, accompanied by the
hydrolysis of the silicate network. On the other hand, deposition
of silicate material on the glassware may take place. Those
phenomena will result, after a certain number of cleaning cycles,
to damages on the glassware, such as turbidity, scratches, streaks
and the like.
[0003] It is known that silicate compounds could be active against
leakage of minerals from glass compositions. However, deposition of
silicate material on the surface of glassware would be
increased.
[0004] There are different approaches in the prior art proposed for
the solution of above identified problems.
[0005] One approach is the use of zinc, either in metallic form
(U.S. Pat. No. 3,677,820) or in the form of zinc compounds. The use
of soluble zinc salts for inhibition of corrosion of glassware in
automatic dishwashing processes is, for example, disclosed in U.S.
Pat. No. 3,255,117.
[0006] There are, however, various disadvantages of the use of
soluble zinc salts, in particular formation of precipitates of
insoluble zinc salts with other ions in the wash liquor or rinse
water. Thus, the use of insoluble zinc compounds for the inhibition
of corrosion of glassware in automatic dishwashing processes has
been proposed in European Patent Application EP 0 383 480 A1, EP 0
383 482 A1 and EP 0 387 997 A1. More particularly insoluble zinc
salts such as zinc silicate, zinc carbonate, zinc oxide, basic zinc
carbonate, zinc hydroxide, zinc oxalate, zinc monophosphate and
zinc pyrophosphate have been proposed.
[0007] With these prior art compositions, it is disadvantageous
that, due to the low solubility, or even insolubility, of the zinc
compounds, it is difficult, if not impossible, to ensure an
continuously sufficient amount of active corrosion inhibiting agent
in the wash liquor or rinse water. Moreover, due to the high
specific density of above mentioned insoluble zinc salts,
separation problems of powder mixtures or deposition problems with
liquid mixtures have occurred.
[0008] WO 97/11151 discloses glassy particles containing agents
useful for laundry and cleaning products. Amongst others, material
care agents are disclosed such as usual corrosion inhibitors such
as paraffin oil, benzotriazole, and the like. The agents are
encapsulated in glassy particles derived from at least partially
water-soluble hydroxylic compounds such as sucrose, glucose and
maltodextrin. No zinc-containing water-soluble glass compositions
are disclosed therein.
[0009] WO 00/39259 discloses the use of water-soluble glasses as
corrosion protection for glassware. This water-soluble glass
composition comprises at least one compound, which in cleaning
and/or rinsing cycles of a dishwashing machine releases a corrosion
inhibiting agent. The solubility of the glass is defined by a mass
loss of at least 0.5 mg under specified conditions. Amongst others,
zinc-containing glasses are disclosed. In preferred embodiments,
the glass building component is preferably phosphorous pentoxide
and additionally comprises at least one alkali oxide. The examples
disclosed therein are characterised by a content of SO.sub.3 of
around 20%.
[0010] However, the glass composition disclosed in WO 00/39259
which is based on ZnO (which is presently believed to be a very
effective glassware-protecting agent) turned out to be
unsatisfactory for manufacture of a consumer appealing product. In
fact, although it is possible, under certain conditions, to
manufacture a transparent glass from the composition, this glass
looses its transparency rapidly after some dishwashing cycles
developing an unappealing appearance.
[0011] Related compositions obtained by variation of the components
resulted in problems of producing a transparent glass in a
continuous manufacturing process, which is required for production
of large amounts of the glass product. In such processes, the raw
materials for glasses are molten in a furnace at temperatures where
they form a liquid glass melt with viscosities from 1 to 1000 dPas
(100 dPas characterises the well know "Melting Point") Afterwards
the melt is continuously slowly cooled down and remains during a
long period working temperature range where it shows a viscosity of
10.sup.4 to 10.sup.8 dPas. This is called the processing range of
glass, determined by the "Working Point", where the liquid glass
shows a viscosity of 10.sup.4 dPas and the "Littleton Point",
10.sup.7,6 dPas, where the shape of glass is formed by pressing
or/and blowing. Finally, the composition reaches the glass
transition temperature range (T.sub.g) where its viscosity
increases becoming a solid material. In this range ("Annealing
Point", viscosity of 10.sup.13 dPas and "Strain Point" 10.sup.14,6
dPas) tensions could be minimised due to annealing.
[0012] The time during which the glass remains within the working
temperature range facilitates devitrification of the glass
formulation. In non-continuous processes (such as those employed in
the manufacture of optical glasses or glasses used as fillers for
plastics), the glass is quickly cooled down after it comes out of
the furnace and therefore devitrification does usually not occur.
The formulation of the glass is, however, much more critical, when
manufacturing transparent glasses in a continuous process with
above described prolonged cooling down periods.
[0013] Thus, it is an object of the present invention to provide
for a zinc-containing, water-soluble glass composition for use as a
corrosion inhibiting product in an automatic dishwashing process
which allows production of transparent glass in a continuous
manufacturing process which glass maintains its transparency upon
dissolution over a sufficient number of dishwashing cycles.
[0014] This object is solved by a zinc-containing, water-soluble
glass composition comprising from 41 to 54 mole % of
P.sub.2O.sub.5, 10 to 30 mole % of alkali oxides, up to 5 mole % of
SO.sub.3 and up t 25 mole % of ZnO.
[0015] In a preferred embodiment of the inventive glass composition
not more than 40 mole %, preferably not more than 20 mole%, most
preferably not more than 1 Omole % of the total amount of alkali
oxides in the glass formulation is constituted by one or more
members of the group consisting of Li.sub.2O and Na.sub.2O.
[0016] Preferably, the inventive composition additionally comprises
at least one alkaline-earth oxide with a total amount of
alkaline-earth oxides of less than 20 mole %, preferably less than
10 mole % and, most preferably less than 5 mole %.
[0017] Also preferably, the inventive composition additionally
comprises at least one oxide of antimony or arsenic with a total
amount of such oxides of less than 5 mole %, preferably less than 3
mole %, most preferably less than 1 mole %.
[0018] The inventive composition may comprise oxides of an element
from the group consisting of silicium, germanium, tin and lead with
a total amount of such oxides of less than 10 mole %, preferably
less than 5 mole %, most preferably less than 3 mole %, wherein no
single of such oxides is present in an amount exceeding 5 mole %,
more preferably 2 mole %.
[0019] Even more preferably, the inventive composition additionally
comprises at least one oxide of an element selected from the group
consisting of aluminium and boron with a total amount of such
oxides of from 0.1 to 10 mole %, preferably from 0.2 to 5 mole %,
most preferably from 0.3 to 3 mole %.
[0020] It is also preferred that the glass compositions according
to the present invention do not comprise more than 0.5 mole % of
oxides of elements from the group IIIb of the Periodic System of
Elements (i.e. the group comprising Scandium, Yttrium, the
Lanthanide series and the Actinide series).
[0021] The presently most preferred composition according to the
invention consists of from 41 to 54 mole % of P.sub.2O.sub.5, from
10 to 30 mole % of alkali oxides, up to 5 mole % of SO.sub.3, up to
25 mole % of ZnO, less than 5 mole % of alkaline-earth oxides, and
from 0.3 to 3 mole % of oxides of elements selected from the group
consisting of silicon, aluminium and boron.
[0022] In the most preferred embodiment of the invention, the
composition is present in the form of a transparent shaped body,
preferably manufactured by continuous glass manufacturing processes
like casting, pressing or blowing.
[0023] In an alternative, the composition is present in a
comminuted form, preferably either manufactured by breaking of thin
glass plates or by milling, wherein the milled glass most
preferably has an average particle size of not more than 500
microns.
[0024] The invention is specifically related to the use of the
inventive glass composition for inhibition of corrosion of
glassware in an automatic dishwashing process, particularly to the
use of a transparent glass composition, which remains transparent
upon dissolution.
[0025] Thus, the invention is also related to processes for
inhibition of corrosion of glassware in an automatic dishwashing
process, either characterised by contacting the glassware, in an
automatic dishwashing machine, with wash liquor and/or rinse water
containing an effective amount of the inventive composition, or by
providing the composition, in particular in the form of a shaped
body, such as a glass block drop casted and pressed in a continuous
manufacturing process, at an appropriate place within an automatic
dishwashing machine being accessible for the wash liquor and/or
rinse water.
[0026] Very surprisingly, only the specific selection of components
in their indicated ranges simultaneously fulfils the requirements
of releasing ZnO during the dishwashing cycles in an amount enough
to ensure glassware corrosion protection, providing for a
dissolution rate of the glass enabling to use a block of reasonable
weight for a reasonable number of washing cycles (for example, 40 g
for 60 cycles), and allowing manufacture of a transparent glass
block in an continuous manufacturing process which glass block does
not loose its transparency during a sufficient number of
dishwashing cycles.
[0027] Although a multitude of glass formulations is known from the
prior art, we are presently not aware of any such composition with
this specific choice of components in the specified ranges. In
particular, above mentioned advantageous features enabling the
desired use of the glass composition for manufacturing a consumer
appealing glass product for inhibition of corrosion of glassware in
automatic dishwashing has neither been anticipated nor obvious for
someone skilled in the art from the prior art documents related to
glass formulations.
[0028] The compositions as exemplified in the following Table have
been produced in a continuous commercial glass pressing processing
as outlined hereinabove. It is easily possible to manufacture
shaped bodies of transparent glass with a weight of about 40 g.
When used an automatic dishwashing machine, the glass block was
completely dissolved after several dishwashing cycles. For example
1 a glass block with the dimensions (1.times.5.times.3) cm.sup.3
was completely dissolved after 60 cycles in the dishwasher, if you
choose the conditions described in prEN 12875-1 with Calgonit
Powerball Tab as detergent. No loss of transparency of the glass
block was observed over this time period.
[0029] The glass corrosion inhibiting activity of these glass
blocks were tested according the methods as described in detail in
WO 00/39259. The results were found to be at least equal, in case
of the composition according to Example 1 even significantly
better.
1TABLE Component Exp. 1 [mole %] Exp. 2 [mole %] Exp. 3 [mole %]
P.sub.2O.sub.5 50 45 43 Na.sub.2O 1 0 0 Li.sub.2O 0 3 0 K.sub.2O
27.5 25 29 ZnO 14.5 15 19 CaO 3 5 0 SO.sub.3 0 4.5 3
Sb.sub.2O.sub.3 0 0.5 0 SiO.sub.2 2 0 3 Al.sub.2O.sub.3 0.5 0 1
B.sub.2O.sub.3 1.5 2 2 Total 100 100 100
[0030] The features disclosed in the foregoing description, and the
claims may, both separately and in any combination thereof, be
material for realising the invention in diverse forms thereof.
* * * * *