[Field of the invention]
5 [ o o 1] The present invention relates to a com position comprising a wax, a
cationic surfactant, and an acid, wherein the molar ratio between the acid and the
cationic surfactant is more than 1.
[ 002] More particularly the present invention relates to the use of a cationic
wax dispersion for improving the external surface protection of glass containers and
10 a process for bringing scratch protection for returnable glass containers.
[Technical problem]
[003] Hollow glass containers are produced from molten glass in molds at
high temperatures. As the surface of these containers is fragile and in order to
15 preserve the strength of the glass and to prevent any direct glass-to-glass contact
of the respective containers to avoid damage, they are directly surface coated
after forming of the container.
[004] Indeed, in the industry of glass containers, for example glass
packaging containers, coatings are applied to improve and maintain their quality.
2 o Without coating, the glass articles can be easily damaged already during the
manufacturing process, and this affects the appearance and weakens the glass
articles.
[005] Such a coating includes tin or titanium or other heat decomposable
metallic or organometallic based compounds. This is the basis of the coating
25 needed for protection of the glass container surface from damage such as
abrasions and scratches, which result in a loss of strength for the glass container.
The need for high tensile strength in a glass container is particularly acute when
containers are mass-produced, and thus move rapidly in close proximity along
high speed conveyor lines.
30 [006] Nowadays, in glass container manufacturing, a two-step coating
process is implemented in order to obtain scratch resistance and slipperiness of
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the glass containers. So, the glass containers typically receive two surface
coatings, one at the hot end, just before annealing and one at the cold end just
after annealing.
[ 007] In the first step, the so-called hot-end coating (HEC) is applied by
5 means of chemical vapor deposition (CVD) of a metal containing compound on
the freshly formed, hot, and single or double line positioned glass containers. This
first step is normally carried out at a temperature ranging from 450°C to 650°C
and conduct to a thin layer of metal oxide.
[ oos] In a second step, the so-called cold end coating (CEC) is applied,
10 usually by spraying means, in form of an aqueous dispersion, when the glass
containers have cooled down to a temperature of approximately 1 00°C. Usually,
partly oxidized polyethylene (PE) wax dispersions are applied. With this additional
coating on glass containers surface, a long-lasting protection is provided,
consisting in scratch resistance and prevention of scuffing of glass surfaces during
15 filling and transportation.
[009] Nowadays, when applying the CEC, it is common to use in an
autoclave process said partly oxidized PE wax dispersions. These dispersions are
dispersed in water by aid of a suitable surfactant. When done at optimum
conditions, a fine dispersion of said wax is obtained. Depending on the type of
2 o surfactant, non-ionic or ionic type of dispersion is obtained. Non-ionic type
surfactant is commonly used, often ethoxylated alcohols, to minimize effect of pH
and hardness of the water used for preparing the final dilution for application.
[ 0010] The aqueous dispersion is delivered in concentrated form, in order
to avoid useless transportation of water, and is diluted to the required
25 concentration in the filling plant. The dispersion is strongly diluted (generally 10 to
200 times with water) and has to stay stable during the dilution and application.
This is even more critical at elevated temperatures if dilution is done with warm
water or heated before application.
[0011] The water quality changes around the world and the quality of the
30 water is not the same everywhere. This implies variation of salts and ions and their
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respective concentration and pH of the water intended for dilution. These salts or
ions can influence the stability during dilution. Therefore, it is often preconized to
use demineralized water for the further dilution. This would imply a water treatment
system, which is not possible all around the world. It is much more convenient to
5 use local water from the place where the plant is located.
10
15
[ 0012] Another problem is, if the diluted coating composition is not stable,
it can cause plug in the coating application equipment, negatively affect the
application quality and might cause downtime of the plant.
[0013] An objective of the present invention is to provide a coating
composition for glass containers that can be easily diluted with any kind of water
and avoid the installation of a water treatment system, and is stable during and after
dilution.
[0014] Another objective of the present invention is provide a process
wherein any kind of water used in the industry, in particular tap water, can be used
to dilute a coating composition for glass containers.
[0015] Still another objective of the present invention is to efficiently reduce
20 downtime of coating equipment and plugs by using a stable coating composition
that can be diluted with tap water.
Brief description of the invention
[0016] Surprisingly it has been discovered that a coating composition for
25 applying a coating on surface of glass containers comprising:
a) a wax
b) a cationic surfactant
c) an acid
wherein the molar ratio between the acid and the cationic surfactant is more
30 than 1, solves the above mentioned problems.
5
10
15
20
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Detailed description of the invention
[ o o 17] In a first aspect, the present invention relates to a com position
comprising:
a) a wax
b) a cationic surfactant
c) an acid
wherein that the molar ratio between the acid and the cationic surfactant is more
than 1.
[0018] In a second aspect, the present invention relates to a preparation
process of a coating composition comprising the step of mixing a wax, with a cationic
surfactant and an acid, the molar ratio between the acid and the cationic surfactant
being more than 1 .
[0019] In a third aspect, the present invention relates to a process of applying
a coating on the surface of glass container comprising a step i) of applying the
composition of the invention on a glass surface, preferably the glass surface of a
container.
[0020] According to another aspect, the present invention relates to the use
of the composition according to the invention, as a cold-end coating on a glass
surface.
[ 0021] By the term "wax" it is meant an organic compound that comprises
25 long alkyl chains, having a melting above 45°C.
[ 0022] By the term "dispersion", it is meant a colloidal system with a
continuous liquid phase and a discontinuous second phase that is distributed
throughout the continuous phase. After the application of the coating material the
continuous liquid phase evaporates and the discontinuous phase forms the coating.
30 [0023] By "any kind water'' it is meant water that can contain high
concentration of salts. Preferably, the water is tap water.
[0024] By the term "surfactant", it is meant a surface active agent, which
exhibits some superficial or interfacial activity.
5
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[0025] By saying that a range is from x to y in the present invention, it
is meant that the upper and lower limit of this range are included, equivalent to at
least x and up to y.
[0026] The composition of the invention is preferably a coating composition,
in particular a coating composition for applying to a glass surface, in particular the
glass surface of a container.
[ 0027] Preferably, the composition of the invention is an aqueous dispersion.
10 [ 0028] The wax of the composition is chosen among natural and synthetic
waxes or mixtures thereof.
[0029]
[0030]
The waxes can be pure or mixed with one or several oils.
Natural waxes are chosen among fatty acids alkyl esters wherein the
alcohol is a primary one and mixture thereof. Preferably, the natural wax is a
15 Carnauba or a Candelilla wax or mixture thereof.
[ 0031] Preferably, the synthetic wax is chosen from the group consisting of
partly oxidized polyethylene waxes having an acid number ranging from 1 mg
KOH/g to 50 mg KOH/g, preferably from 10 mg KOH/g to 30 mg KOH/g, and even
more preferably having an acid number of 20 mg KOH/g.
2 o [ 0032] When the composition of the invention is a concentrated aqueous
dispersion, it can comprise from 5 to 25 wt%, preferably from 8 to 25 wt%, more
preferably from 8 to 20 wt% and even more preferably from 1 0 to 15 wt% of wax
relative to the total composition weight.
[ 0033] When the composition of the invention is a coating dilution, it
25 comprises between 0.05wt% and 1wt% of wax, preferably between 0.2 wt% and
0.5wt% of wax relative to the total weight of the composition.
[0034] By the term "cationic surfactant" it is meant the cationic surfactant itself
or its precursor that can transformed by generation of a cation in the surfactant.
30 Preferably, the cationic character of the surfactant is created by contacting the
amine precursor with an acid.
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[0035]
formula (1 ):
Preferably, the cationic surfactant (or its precursor) presents the
( 1)
5 Wherein:
at least one of R1, R2 or R3 represents an alkyl group, linear or branched,
optionally ethoxylated,
at least one of R 1, R2 or R3 represents an hydrogen atom.
optionally, one of R1, R2 or R3 represents an alkyl amine group, ethoxylated
10 or not.
Preferably, the alkyl group comprises between 1 and 35 carbon atoms, preferably
between 12 to 26 carbon atoms, more preferably between 14 and 22 carbon atoms,
and even more preferably 16 carbon atoms.
[ 0036] Preferably, when the alkyl group is ethoxylated, it contains at most 5
15 ethoxylations, most preferably has 2 ethoxylations.
[ 0037] Preferably, the alkyl amine group comprises between 1 and 35 carbon
atoms, preferably between 12 to 26 carbon atoms, more preferably between 14 and
22 carbon atoms, and even more preferably 16 carbon atoms.
[ 0038] Preferably, when the alkyl amine group is ethoxylated, it contains at
2 o most 5 ethoxylations, most preferably has 2 ethoxylations.
[ 0039] Cationic surfactants are preferably chosen in the group consisting of
mono alkyl amine, di alkyl amine, ethoxylated alkyl amine and alkyl diamines (such
as Dinoram 0® and Dinoram S® from CECA).
[ 004 o] When the composition of the invention is a concentrated aqueous
25 dispersion, it can comprise from 1 to 15 wt%, preferably from 2 to 10 wt%, more
preferably from 3 to 6 wt% of cationic surfactant relative to the total composition
weight.
[ 0041] When the composition of the invention is a coating dilution, it can
comprise from 0.005 to 1.5 wt%, preferably from 0.01 to 1 wt%, more preferably
30 from 0.015 to 0.6 wt% of cationic surfactant relative to the total composition weight.
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[ 0042] The acid of the coating composition is a Bronsted acid having the
general formula HA, i.e. an acid that can release a proton (H+).
[0043] The acid can be a mineral acid or an organic acid.
[0044] Preferably, the acid is chosen from the group consisting of
5 hydrochloric acid, sulphuric acid, formic acid, acetic acid, propionic acid, butyric
acid, malonic acid, itaconic acid and fumaric acid.
[ 0045] Preferably, the mineral acid is chosen from the group consisting of
hydrochloric acid and sulphuric acid.
[0046] Preferably, the organic acid comprises at most 12 carbon atoms,
10 preferably at most 10 carbon atoms, more preferably at most 6 carbon atoms, more
preferably comprises at most 4 carbon atoms, and even more preferably comprises
at most 3 carbon atoms.
[0047] Preferably, the organic acid is chosen from the group consisting of
formic acid, acetic acid, propionic acid, butyric acid acid, malonic acid, itaconic acid
15 and fumaric acid, preferably is acetic acid.
[ 004 8] The solubility of the acid in water is at least 10 g/1, preferably at least
15 g/1, more preferably at least 20 g/1.
[ 004 9] When the composition of the invention is a concentrated aqueous
dispersion, it can comprise from 1 to 15 wt%, preferably from 2 to 10 wt%, more
2 o preferably from 3 to 6 wt% of acid relative to the total composition weight.
[ 0050] When the composition of the invention is a coating dilution, it can
comprises from 0.005 to 1.5 wt%, preferably from 0.01 to 1 wt%, more preferably
from 0.015 to 0.6 wt% of acid relative to the total composition weight.
25 [ 0051] By "the molar ratio between the acid and the cationic surfactant is
more than 1 ", it is meant that molar quantity of the acid exceeds the molar quantity
of the cationic surfactant.
[ 0052] Preferably, the molar ratio between the acid and the cationic surfactant
is at least 1.01, preferably at least 1.1, more preferably at least 1.2, more preferably
30 at least 2, and even more preferably at least 3.
[ 0053] Preferably, the molar ratio between the acid and the cationic surfactant
is at most 5.
[ 0054] Preferentially, the composition comprises one or more additional
additives, preferably chosen in the group consisting of biocides, bactericides,
5
10
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preservatives, ester alcohol, glycol ether, dyes, emulsion destabilizers, perfumes,
odorants, UV absorbers, light absorbers, impact absorbers, surfactants other than
sorbitan esters, oils other than mineral oils and the like.
[0055] The composition of the invention can be a coating dilution which will
be directly applied as a coating, or a concentrated aqueous dispersion that will be
later diluted to obtain a coating dilution. The coating dilution may be applied to a
glass article, for example a glass container.
[0056] By "concentrated aqueous dispersion", it is meant that the aqueous
dispersion will be later diluted to obtain a coating dilution. The terms "concentrated
aqueous dispersion is also referred hereinafter as "aqueous dispersion".
[0057] Preferably, the coating dilution comprises from 0.5 to 10 wt% of the
concentrated aqueous dispersion relative to the total weight of the coating dilution.
15 In other words, the concentrated aqueous dispersion is diluted 10 to 200 times to
obtain the coating dilution.
[ 0058] Preferably, the composition of the invention is diluted in solvent to
obtain the coating dilution. Preferably, said solvent is water, more preferably tap
water. Preferably, the composition of the invention comprises between 90 and 99.5
20 wt% of solvent relative to the total weight of the composition.
[ 0059] The present invention also relates to the use of the composition
according to the invention for the preparation of a coating dilution, in particular with
tap water.
[ 0060] The present invention also relates to the use of the composition
25 according to the invention as a coating dilution.
[ 0061] Still another object of the present invention is a coating dilution
comprising the composition according to the invention.
[ o o 62] Another object of the present invention is the use of the com position
according to the invention, as a cold-end coating on a glass surface.
3 o [ o o 63] Another object of the present invention is a preparation process of a
composition of the invention, comprising a step of mixing a wax, with a cationic
surfactant and an acid, the molar ratio between the acid and the cationic surfactant
being more than 1 .
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[0064] The wax, the cationic surfactant, the acid and the molar ratio are as
defined above.
[0065] The wax, the cationic surfactant and the acid can be mixed altogether
or in several steps. Preferably, the wax and the cationic surfactant are mixed in a
5 first step, and the acid is then added. Alternatively, at least a part of the acid is added
while mixing the wax and the cationic surfactant.
10
[ 0066] Preferably, the composition of the invention is an aqueous dispersion.
[0067]
[0068]
[0069]
The acid can be added in one or several steps.
In one embodiment, the acid is added in one step.
In another embodiment, a part of the acid is added when the
concentrated coating dispersion is prepared and a second part of the acid is added,
for achieving the molar excess of the acid, afterwards, preferably during the dilution
step.
[ o o 7 o] The acid in excess to the surfactant can be added to the solvent,
15 preferably to the water, used for dilution.
20
[ o o 71] The present invention also pertains to a process of applying a coating
on the surface of glass container comprising a step i) of applying the composition of
the invention on a glass surface, preferably the glass surface of a container.
[0072] Said step i) can be made by contact between the composition of the
invention and the glass surface. This contact is preferably achieved by a coating
application method, preferably chosen in the group consisting of spraying, dipping
and the use a coating applicator.
[0073] Preferably, said step i) is implemented on a glass surface at a
25 temperature ranging from 1 ooc to 150°C. Preferably, when the step i) is applied
in a filing line on a glass surface, the temperature ranges from 15°C to 70°C, most
preferably between 20°C and 40°C.
[ 007 4] Advantageously, means for applying said formulation or said coating
dilution to a glass surface by spraying comprise spraying means.
30 [0075] According to one embodiment, means for applying said formulation
or said coating dilution to a glass surface by dipping comprise a recipient
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containing said formulation or said coating dilution in which the containers are
dipped.
[0076] The coating applicator can be a brush, capillary, sponge, fiber or the
like. The coating material is applied on the surface of the glass article via the
5 contact area between the coating applicator and the glass article surface.
10
15
20
[0077] Preferably, the coating process is for coating a glass container, and
the coating process further comprises a previous step i') of applying a metal oxide
treatment to the glass surface.
[0078]
[0079]
Advantageously, the metal is chosen from tin and titanium.
Another object of the present invention is a glass surface obtainable
by the coating process according to the invention.
[ 0080] Preferably, the glass surface is a glass container, more preferably,
a glass bottle.
Examples
[ 0081] Example 1
[0082] Kercoat® 500 from Arkema containing 0.013 mol of acetic acid and
0.015 mol of cationic surfactant was used to prepare dilutions at a concentration of
1% (Compositions A and D), 2% (Compositions Band E) and 3% (Compositions C
and F) by weight of Kercoat® 500 relative to the total weight of the dilution.
[ 0083] In table 1, the water used for the dilution came from the tap water in
25 Arkema's premises in Vlissingen, Netherlands. In table 2, the used water was
demineralized water. The dilutions were stored at 65°C for one week and the
stability was evaluated.
[ 0084] To evaluate the stability of the composition, the turbidity of the
compositions was measured using the standard ISO 7027. The results are given in
30 FNU (Formazin Nephelometric Units).
[ 0085] The results are shown in Tables 1 and 2 below:
5
10
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[0086] [Table 1]
Table 1 Tap Water Arkema Vlissingen
Dilution stability measurement in FNU
Days Composition Composition Composition
A B c
0 21 38 51
0,25 888 127 54
1 1300 1300 64
2 1300 1300 95
3 1300 1300 162
6 1300 1300 938
7 1300 1300 1300
[0087] [Table 2]
Table 2 Demineralized water
Dilution stability measurement in FNU
Days Composition Composition Composition
D E F
0 18 33 45
0,25 18 33 43
1 18 32 44
2 17 31 42
3 18 31 41
6 19 33 42
7 18 32 42
[0088] The results show that cationic wax dispersions are not stable when
diluted in tap water, contrary to what is observed when demineralized water is used.
[0089]
[0090]
Example 2
Example 1 using tap water was reproduced (Compositions A to C),
and the compositions were supplemented with 0.017 mol (i.e. to a total content of
0.030 mol in the composition), 0.033 mol (i.e. to a total content of 0.046 mol in the
composition) and 0.050 (i.e. to a total content of 0.063 mol in the composition) of
acetic acid respectively.
15 [ 0091] The results are shown in table 3 below:
[0092] [Table 3]
I Dilution stability measurement in FNU
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Days Composition Composition Composition
A B c
+ 0.017 mol + 0.033 mol + 0.050 mol
of acetic of acetic of acetic
acid acid acid
0 19 37 50
1 21 34 45
2 27 34 45
3 27 34 45
6 103 34 45
7 461 34 45
5 [0093] A comparison of examples 1 and 3 shows a significant increase in
stability of the composition when acid is present at a ratio of more than one relative
to cationic surfactant.

Claims
1. A composition comprising:
a) a wax
13 PCT/EP2021/067315
5 b) a cationic surfactant
c) an acid
wherein the molar ratio between the acid and the cationic surfactant is more
than 1.
2. The composition according to claim 1, characterized that the molar ratio
10 between the acid and the cationic surfactant is at least 1.01, preferably at least
1.1, more preferably at least 1.2, more preferably at least 2, and even more
preferably at least 3.
3. The composition according to claim 1 or 2, characterized that the cationic
surfactant is chosen from mono alkyl amine, di alkyl amine, ethoxylated alkyl
15 amine and alkyl diamines.
4. The composition according to claim 1 or 2, characterized that acid is chosen
from the group consisting of hydrochloric acid, sulphuric acid, formic acid, acetic
acid, propionic acid, butyric acid acid, malonic acid, itaconic acid and fumaric
acid.
20 5. The composition according to claim 1 or 2, characterized that wax is chosen
from fatty acids alkyl esters wherein the alcohol is a primary one and mixture
thereof, preferably, is a Carnauba or a Candelilla wax or mixture thereof.
6. The composition according to any of claims 1 to 5, characterized that the
25 composition is in form of an aqueous dispersion.
30
7. The composition according to any of claims 1 to 5, comprising from 5 to 25 wt%,
preferably from 8 to 25 wt%, more preferably from 8 to 20 wt% and even more
preferably from 10 to 15 wt% of wax relative to the total composition weight.
8. A composition as defined in any of claims 1 to 7, comprising between 90 and
99.5 wt% of solvent relative to the total weight composition.
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9. A preparation process of a coating composition, comprising a step of mixing a
wax, with a cationic surfactant and an acid, the molar ratio between the acid and
the cationic surfactant being more than 1.
5 10. A process of applying a coating on a glass surface comprising a step i) of
applying the composition as defined in any of claims 1 to 8 on a glass surface,
preferably the glass surface of a container.
11. The use of the composition according to any of claims 1 to 8, as a cold-end
10 coating on a glass surface.
15
12. Glass surface, preferably glass container, and even more preferably glass
bottle obtainable by the process as defined in claim 1 0.