Note: Descriptions are shown in the official language in which they were submitted.
z~
The present i~vention relates to a process for
rendering substrates, particularly solid, gel-like or glass-
like substrates wettable.
It is known that an equation of state
F ( ~s~ ~f/ ~sf)
exists between the interfacial-energy fundamental quantities,
namely the surface tension of a substrate, for example, of a
solid ~s, the surface tension of a liquid af, and the inter-
facial tension Y sf between substrate and liquid. It is also
known that the wettability of a substrate by a liquid depends
on the ratio of the surface tensions of substrate and liquid
and that the wettability of a substrate can be improved either
}~y reducing the surface tension of the liquid or by increasing
the surface tension of the substrate. The decrease of the
surface tension of the liquid can be brought about, for
example, by adding emulsifiers to the li~uid, a measure used
in a large number of processes of the prior art. The increase
of the surface tension of solids can be attained by a special
surface treatment such as that ~lisclosed, for example, in
Swiss Patent 397,237, German Patent 1,519,547, Canadian Patent
802,097, Italian Patent 731,137, French Patent 1,402,310,
British Patent 1,079,391 and U. S. Pa-tent 4,139,660. However,
the process mentioned last, which has proved to be excellent
for the treatment of spectacle lenses and for the treatment
of visors of diver's equipment, is not suitable for articles
which are subject to mechanical stress, as for example, abra-
sion! If the treated surface is eroded by abrasion, then the
subadjacentnon-treated layer,which, like the ori~inal material,
is wettable only with difficulty or not at all, i.s exposed.
This has the result that -the improvement of the we-ttability
attained by the surface treatment is eliminate~ after short-
~73Z;~
time mechanical stress and the surface treatment must be
repeated.
Therefore, the present invention provides a process
by means of which the wettability of substrates is permanently
improved so that it is maintained even under mechanical stress.
According to the present invention there is provided
a process for rendering a substrate wettable, which comprises
incorporating into the substrate as active substance, at least
one organo-metallic compouna of an element of the fourth main
or secondary group of the Periodic system of the elements,
which substance causes an increase in energy of the substrate
and is not soluble in the substrate, in an amount, which causes
an appreciable increase in energy and thus an increase of the
surface tension of the substrate structure, said substance
being homogeneously distributed in the substrate while form-
ing finely divided punctiform aggregates.
An improvement of the wettability which is uniform
within the entire substrate can be attained by this process
so thatthe subadjacent layers, which are exposed as, the surface
is worn off, have the same wettability as the original surface.
It is essential that the compounds serving as the active
substance are applied not only to the surface of the substrate
but that they are also distributed within the substrate. The
efficiency of the active substance increases with the degree
of distribution. This means that the more finely divided the
active substance the greater will be the efficiency of the
active substance. Therefore, particle sizes of approximately
cm down to the colloidal distribution, i.e., to particle
sizes of 10 to 10 7cm are recommended. It follows from what
has been mentioned hereinbefore that the more finely divided
the active substance the smaller will be the added amount of
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3~
active substance. For sufficiently fine distribution, for
example, for particle sizes < 10 cm, the result aimed for
can be attained with added amounts of 3 to 5% by weigh~, rela~
tive to the weight of the substrate. The added amount of
active substance usually depends on the degree of distribution
and on the kind of substance, particularly on its properties
and intended use. The upper limit of the added amount is
determined by the effect on the mechanical properties of the
substrate. It is generally true that the active substance may
be added only in amounts such that its presence does not
substantially change the structure of -the suhstrate and that
its mechanical properties, particularly its strength, are not
impaired so that i-ts suitability for the intended use is not
detrimentally affected.
Among the compounds of elements of the fourth
principal or secondary group of the Periodic system of elements
which can be used as the activesubstance acetyl acetonate such as
zirconium acetyl acetonates and tin dlchloride di(acetylaceton-
ate) are particularly preferred.
For the selection of the compounds serving as the
active substance it is essential that said compounds are not
soluble in the substrate but that they are incorporated in
the substrate in the form of finely divided punctiform aggre-
gates. In this connection the definition of"punctiform" is
not to be interpreted as a description of the shape of the
aggregates but is merely intended to indicate the contrast to
. ,
a continuous distribution.
The compounds serving as the active substance can be
added to the substrate in the form of solutions, particularly
in organic solvents~ or as suspensions or in the solid form.
The manner in which the active substance is added depends
primarily on the type of substrate to be treated. The active
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73~7
substance can be incorporated by means of conventional mixing
processes. It is only important that a distribution of the
active substance as finely divide~ in the substrate as possible
is attained. Thus, in specific cases it can be advantageous
to treat an iner~ carrier material, for example, a highly
dispersed silica, with the active substance and to incorporate
the carrier material loaded with active substance in the sub-
strate. In this manner an extremely fine and homogeneous
distribution of the active substance in the substrate is
attained, especially since a mono- or bimolecular covering of
the particles of the carrier material with the active substance
is ade~uate. This procedure is recommended particularly in
the cases where the substrate is a plastic material to which
an inert carrier is added in any case in order to improve the
mechanical properties of the substrate.
When treating a substrate formed by two or more
components the procedure can be such that only one component
is treated with the active substance, whereupon ~he treated
component is mixed with the other components.
When applying the process to substrates of polymer
materials such as homo- or co-polymers the active substance
can be incorporatedin thepolymerization when required.
The improvement of the wettability of textiles con-
sisting entirely or partially of synthetic fibres can be
attained by adding the ac-tive substance to the material serving
for the production of the fibres prior to the melt spinning
and by dis-tributing it in said material. The wettability of
textiles consisting of natural fibres, for example, cotton,
wool and silk can be improved by treating the fibres or the
fabric produced therefrom.
Yurthermore when the .substrates are porous or in the
_~ ~} q ?"J'3
~JLY~'~
form of highly dispersed aggregates, the substrates can be
treated with a solution of the active substance or the active
substance can be absorbed by the substrate. These processes
are suitable particularly for highly dispersed aggregates
which are to be used for the production of suspensions. ~n
this manner a substantial improvement of the stability of the
suspension can be attained.
The fact that in practically all the fields of
technology problems resulting from the deficient wettability
of substrates are encountered opens a wide and diversified
field of application.
The most important applications include:
(a) Rendering substrates of polymexs, such as polyethyl-
ene, polypropylene, polyvinyl cllloride, Teflon (a trademark~
and numerous other homo- and co-polymers wettable. This
includes, for example, rendering vehicle tires and tool and
machine parts of plastics wettable;
(b) Rèndering substrates of rubber and rubber-li~e
- materials wettable, for example, those of vehicle tires;
(c) Rendering substrates of glass-like produc-ts wettable,
such as those of optical instruments, vehicle windows as well
as of tool and machine parts;
(d) Rendering building materials, particularly cement
and concrete products wet-table;
(e) Rendering road surfaces wettable;
(f) Rendering textiles we-ttable, i.e., those consisting
of natural fibres and those consisting entirely or partially
of synthetic fibres, in order to improve their wearing proper-
ties; and
(g) Stabiliæing suspensions, particularly in dye chemis-
try, for example, for improving the dyeing properties and for
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stabilizing dispersion dyes, in the production of catalysts,
making pesticides ready ~or use as well as in pharmaceutical
chemistry.
The above l.st ls not limitative it is merely meant to
illustrate the diversity o~ feasible uses.
For the use of the process of the present invention
for rendering substrates of polymers wettable or for improving
their wettability various methods are suitable, for example;
a) Incorporating the active substance in the polymer
material prior to forming;
b) Treating the monomer or one of the monomers with the
active substance prior to the polymerization and tl~us incorpor-
ating the active substance in the polymerization and
c) When fillers are used, treating the filler with
the active substance and subsequently distributing the filler
in the polymer.
The last mentioned method is suitable particularly
for the production of vehicle tires of plastics or rubber. In
this case it is advisable to treat the carbon blac~ used as
filler with the active substance and -to add the carbon black
thus treated prior to the forming operation, or in the case
of rubber prior to the vulcanization, and to distribute the
carbon black in the plas-ticsor rubber material.
When rendering building materials, particularly
cement and concrete products wettable, the procedure is suit-
ably such that the aggregates, for example, sand, are treated
with the active substance prior to the mixing operation. The
active substance can be applied in both the solid form and
in solution form. Another possibility is that the ac-.ive
substance is added to the mixing water. The amount of ac-tive
substance should be approximately 5 to 20% by weigllt, relative
to the total weight of the mixture. Not only can a higher
density be attained for concrete in this manner but also an
improved adhesion of the vehicle tires in the case of road
coverings of concrete an~ an improved adhesion of plaster to
buildings.
For road coveringSof asphalt or tar products an
improvement of the wettability of the coveringsand~thus an
improved adhesion of vehicle tires can be attained by treating
the aggregates, for example, sand, with the active substance
prior to mixing them with -the asphalt or tar products. The
optimal amounts o addition can be easily determined by routine
tests.
In order to attain a permanent improvement of the
wettability and thus of the wearing comfort of textiles consist-
ing entirely or partially of synthetic fibres, it is advisable
to carry out the trea-tment with the active substance prior to
or during the production of the flbres. The procedure is suit-
ably such that prior to putting the polymers used for producing
the fibres into the melt-spinning apparatus the pol~mers are
treated with the active substance and intimately mixed there-
with, whereupon the mixture thus obtained is subjected to
melt-spinning. The product thus obtained has a subs-tantially
improved wettability, which is permanent and retained even
after a plurality of washing operations and after mechanical
stress of the fabrics produced from the fibres. Therefore,
with respect to the wearing comfort, textiles treated in this
manner are superior to fabrics impregnated in the conventional
manner.
For textiles made from natural fibres, for example,
cotton, wool or silk, it is advisable to treat the fibres or
the fabrics produced therefrom with solutions of t~le active
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32~7
substance and then to wash the fibres or fabrics, when required,
at elevated temperature, for example, at boiling temperature.
With regard to the special importance of the appli-
cation of the process according to the present invention to
the stabilization o~ suspensions the stabilizing effect attain-
ed by the process according to the present invention will be
explained hereafter by the description of tests carried out
with carbon suspensions~ The results obtained in these tests
can also be applied, without any difflculty, to other suspen-
sions, for example, dye suspensions and catalyst suspensions.Furthermore, these results open new possibilities for readying
pesticides for use.
Stabilization of Suspensions
The stabilizing effect of a treatment according to
the present invention was demonstrated with the aid of a sedi~
mentation test on suspensions of carbon black and active
carbon in water. Several test series were carried out using
-tindichloride di(acetylacetonate~ (referre~ to hereafter as SnA)
and zirconium acetyl ac~tonate (referred to hereafter as Zr~)
as the active substance. These compounds were added to the
carbon black and to the active carbon in varying amounts in
order to determine the most effective concentrations. The
samples treated with a specific amount of active substance
were compared with an untreated sample. The compounds serving
as the active substance were used in the form of ethanolic
solutions or suspensions. The treatment was carried out by
boiling under reflux for 30 minutes, paying attention to inten-
sive intermixing, for example, by rotating. The solvent was
then evaporated in vacuo or by means of a rotary evaporator
and the residue was dried over P205 or silica gel and then
pulverized. The comparison samples were only treated with
ethanol, freed from the solvent, dried and pulverized.
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1~7~
For carrying out the sedimentation test, samples of
0.3, 0.5, 0.6, 1.0 and 1.5g of carbon black or active carbon
(treated and untreated) were mixed each with lOOml of water
in a mixing cylinder (height l9cm), shaken for 10 minutes and
then allowed to stand for a lenythy period for observation.
In some cases an additional preliminary treatment
was carried out, as will be mentioned hereafter.
Test Series I
a) 0 7% (weight/weight) of SnA and ZrA lg of carbon
black, which had been pretreated by washing with CHCQ3 and
subsecluent drying and pulverizing, was mixed with lml of a
solution containing 7mg of SnA in ~6~ ethanol and 7mg of ZrA
in 93% ethanol, diluted with 20ml of ethanol and allowed to
rotate for 30 minutes at reflux temperature. The solvent was
evaporated in vacuo and the residue was dried over phosphorus
pentoxide in a desiccator. A comparison sample was treated
with ethanol without adding active substance and further treat-
ed in the same manner.
For carrying out the sedimentationtest portions
0.5g of the individual samples were mixed each with lOOml of
water in a mixing cylinder (height 19cm) and allowed to stand,
The change of the suspensions in the individua:L cylinders was
observed visualLy. The results were as follows:
Time (min.) ' SnA (0.7%) ZrA (0.7%) Untreated
1 almost deposited almost deposited deposited
3 deposited deposited deposited
b) 6.0% (weight/weight) of SnA and ZrA
The samples were produced in the sarne manller as those
described under a), using each time lml of an ethanolic solu-
tion of SnA or ZrA, which cont,ained 60mg of the cornpound.
_ 9 _
~ 7~ ~J~
Furtherm~re, in the present case the test was not subjected
to a preliminary treatment.
The sedi}nentation test was carried out in the manner
described under (a) with samples containing each 0.5g in lOOml
of water. The results were as follows:
Time (min.) SnA (6.0%) ZrA (6.0%) Untreated
0.5 nontransparent slightly one half
black transparentdeposited
1nontransparent well three
black transparentquarters
deposited
2 faintly furtheralmost
transparent settling,entirely
still darkdeposited
settling settlingdeposited
completed, completed,clear
twice as still a
dark as for few suspended
ZrA particles _
The repetition with 7.0% ~weight/weight~ of SnA and
ZrA produced the same result.
c) 10% (weight/weight) of SnA and ZrA
Time (min.) SnA (]0%) ZrA (10%) Untreated___ _ _ _ _ _
0.5one half black one half
depositednontransparent deposited
1three quarters faintlythree quar-
deposited transparentters deposited
2 almost upper almost
completely margincompletely
deposited brightdeposited
threedeposited
quarters clear
deposi-ted
still dark
T _ Series II
a) 12% (weight/weight) of SnA
5g of carbon black were mixed with lOml of a 6%
-- 10 --
~73~7
ethanolic SnA solution, whereupon the mixture was heated under
reflux for 30 minutes. The solvent was then removed by means
of a rotary evaporator and the residue was dried over silica
gel in a desiccator. The sample obtained had a content of
12% (weight~weight) of SnA. For the production of ~he compar-
ison sample 5g of carbon black were treated with lOml of
ethanol in the manner described above and dried.
For carrying out the sedimentation test samples of
0.3g each (treated and untreated) with lOOml of water were
each put into a mixing cylinder (height 19cm) and shaken for
10 minutes. The cylinders were allowed to stand while the
change of the suspensions in the cylinders was visually observ-
ed during the period defined above. The following results
were obtained:
Time (min.) SnA (12%)Untreated
0.25 no changesettling
(black,
nontransparent)
1 no changemostly
(~lack, deposited
nontransparent)
3 no changeonly a few
(black, suspended
nontransparent) particles
left
,
- This result is illustrated by the accompanying
drawings in which the Figures are photographs 1 to 3.
Photograph 1 shows the suspension 0.25 minutes after
mounting the cylinders;
Photograph 2 shows the suspension 1.0 minute after
mounting the cylinders;
Photograph 3 sho~s the suspension 3 minutes after
mounting the cylinders.
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1~32~
The cylinder on the left contains 0.3g of carbon
black treated with SnA (SnA content 12% (weight/we~ght)) in
lOOml of water and the cylinder on the right contalns the
same amount of untreated carbon black.
b) The repetition of the sedimentation test using
1.5g of carbon black (treated as described under (a) and
untreated~ in lOOml of water showed the same result.
c) 20% (weight/weight) of SnA
7.5g of carbon black were treated Wit}l 25ml of a
25% ethanolic SnA solution in the manner described under (a).
A product having an SnA content of 20% (weight/weight) was
obtained. The comparison sample was produced in tne manner
described under (a).
For carrying out the test sedimentation samples of
lg of carbon black each (treated with SnA and untreated), each
sample with lOOml of water were placed in a mixing cylinder
(height 19cm) and mixed on the shaking machine for 5 minutes.
The cylinders were allowed to stand while the change of the
suspensions in the cylinders was ohserved visually. The follow
ing results were obtained:
Time SnA (20%)Untreated
2 minutes nontransparent coarse particles
black (entirecompletely
height)deposited
5 minutes unchangedonly a small
number of
suspended
particles left
10 minutes unchangedminor amount
of suspended
particles
1 hour unchangedextremely small
suspended
particles, almost
~ clear
1 d y _ _ __ un h_n ed _ clearly depos~ted
- 12 -
~7 3i~d)7
The repetition of the sedimentation test with
suspensions having a content of 0.3g o~ carbon black instead
of l.Og showed the same result.
d~ In this case carbon black was replaced by active
carbon ("Carboraffin") and 5g of active carbon were treated
with 15ml of a 6% ethanolic SnA solution in the manner describ-
ed under (a). The product obtained had an SnA content of 18%
(weight/weight). The comparison sample was also produced in
the manner described under (a).
For carrying out the sedimentation test suspensions
containing each 1.5g of active carbon in lOOml of water were
produced. The suspensions were shaken in a mixing cylinder
(height l9cm) for 10 minutes and then observed visually. The
results were as follows:
Time (min.) SnA (lg~) Untrea_ed
nontransparent, translucent
black but intensely
-turbid
unchanged brighter but
not clear
120 upper margin (lcrn) ; continues
slightly translucent to settle
These tests show that amounts as small as6.0% by
weight of active substance have a stabilizing effect but -that
with concentratlons of 10 to 15% by weight a substantially
greater stabilizing effect is attained. Furthermore, it has
also been found that the structure, particularly the porosity
of the substrate and thus the bonding strength for -the active
substance associated therewith influences tlle stabilizing
effect. For the application of this process to otl~er suspen-
sions the optimal amounts of addition of the active substance
can be easily determined by prellm;nary -tests.
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