U.S. patent application number 10/589040 was filed with the patent office on 2007-06-14 for anticorrosion coating composition in aqueous dispersion comprising an organic titanate and/or zirconate.
Invention is credited to Antonio Francisco Iandoli Espinosa.
Application Number | 20070134503 10/589040 |
Document ID | / |
Family ID | 34778680 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070134503 |
Kind Code |
A1 |
Espinosa; Antonio Francisco
Iandoli |
June 14, 2007 |
Anticorrosion coating composition in aqueous dispersion comprising
an organic titanate and/or zirconate
Abstract
The present invention relates to an anticorrosion coating
composition for metallic parts based on particulate metal in
aqueous dispersion comprising an organic titanate or zirconate
compatible in aqueous phase or in organic phase, optionally a
silane-based binder, and water. The present invention likewise
relates to an anticorrosion coating of metallic parts obtained from
the coating composition according to the invention as well as a
metallic substrate provided with this anticorrosion coating. The
invention additionally relates to an aqueous composition of
C.sub.1-C.sub.8 tetraalkyl titanate, intended for the preparation
of a coating composition of a metallic substrate in aqueous
dispersion, as well as the process for preparation of such a
composition.
Inventors: |
Espinosa; Antonio Francisco
Iandoli; (Sao Paulo, BR) |
Correspondence
Address: |
FAY SHARPE LLP
1100 SUPERIOR AVENUE, SEVENTH FLOOR
CLEVELAND
OH
44114
US
|
Family ID: |
34778680 |
Appl. No.: |
10/589040 |
Filed: |
February 10, 2005 |
PCT Filed: |
February 10, 2005 |
PCT NO: |
PCT/IB05/00488 |
371 Date: |
August 10, 2006 |
Current U.S.
Class: |
428/450 ;
106/287.16; 106/287.19; 427/387 |
Current CPC
Class: |
C08G 77/58 20130101;
C09D 5/10 20130101; C09D 5/106 20130101; C23C 22/83 20130101; Y10T
428/31663 20150401; C09D 183/14 20130101; C09D 4/00 20130101; C08K
5/5419 20130101; C09D 5/086 20130101; C09D 7/63 20180101; C23C
2222/20 20130101; C09D 4/00 20130101; C08G 77/00 20130101 |
Class at
Publication: |
428/450 ;
106/287.16; 106/287.19; 427/387 |
International
Class: |
B32B 9/06 20060101
B32B009/06; C09K 15/32 20060101 C09K015/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2004 |
FR |
0401349 |
Claims
1. An anticorrosion coating composition of metallic parts based on
particulate metal in aqueous dispersion comprising, in the
following proportions (percentages by weight): at least one of an
organic titanate and an organic zirconate in an amount from 0.3 to
24%; a particulate metal or a mixture of particulate metals in an
amount from 10 to 40%; a silane-based binder in an amount from 1 to
25%; and water in an amount sufficient to produce 100%; wherein the
sum of the organic titanate and/or zirconate and of the
silane-based binder is between 5 and 25%.
2. The composition according to claim 1, characterized in that
wherein (i) the organic titanate is selected from the group
consisting of titanates compatible in organic phase, compatible in
aqueous phase, and combinations thereof, and (ii) the organic
zirconate is selected from the group consisting of zirconates
compatible in organic phase, zirconates compatible in aqueous
phase, and combinations thereof.
3. The composition according to claim 2, wherein the titanates
compatible in organic phase are C.sub.1-C.sub.8 tetraalkyl
titanates, and the zirconates compatible in organic phase are
C.sub.1-C.sub.8 tetraalkyl zirconates.
4. The composition according to claim 2, wherein the titanates
compatible in aqueous phase are chelated organic titanates, and the
zirconates compatible in aqueous phase are chelated organic
zirconates.
5. The composition according to claim 1 wherein the particulate
metal is selected from the group consisting of zinc, aluminium,
zinc alloys, aluminium alloys, zinc and aluminium alloys, and
combinations thereof.
6. The composition according to claim 1 wherein the silane-based
binder comprises a silane having at least one hydrolysable
function.
7. The composition according to claim 1 wherein the silane includes
an epoxy function.
8. The composition according to claim 7, wherein the silane is
selected from the group consisting of di- or trimethoxysilane with
an epoxy function, di- or triethoxysilane with an epoxy function,
and mixtures thereof.
9. The composition according to claim 1, further comprising 1 to
30% by weight of organic solvent or a mixture of organic solvents,
with respect to the total weight of the composition.
10. The composition according to claim 9, wherein the organic
solvent is selected from the group consisting of glycolic solvents,
acetates, nitropropane, alcohols, ketones, white spirit, and
mixtures thereof.
11. The composition according to claim 1 further comprising 0.1 to
7% by weight of molybdenum oxide, with respect to the total weight
of the composition.
12. The composition according claim 1 further comprising 0.5 to 10%
by weight, with respect to the total weight of the composition, of
an anticorrosion reinforcing agent selected from the group
consisting of yttrium, zirconium, lanthanum, cerium, praseodymium,
in the form of oxides or of salts thereof.
13. The composition according to claim 1 further comprising at
least one of a thickening agent.
14. A method for forming an anticorrosion coating of metallic
parts, the method comprising: obtaining a coating composition
comprising, in the following proportions (percentages by weight):
at least one of an organic titanate and an organic zirconate in an
amount from 0.3 to 24%, a particulate metal or a mixture of
particulate metals in an amount from 10 to 40%, a silane-based
binder in an amount from 1 to 25%, and water in an amount
sufficient to produce 100%, wherein the sum of the organic titanate
and/or zirconate and of the silane-based binder is between 5 and
25%; forming a coating layer by spraying, soaking-draining or
soaking-centrifugation; and subjecting the coating layer to a
baking operation by supply of thermal energy to thereby form the
anticorrosion coating.
15. The method according to claim 14, further comprising, prior to
the baking operation, the coated metallic parts are subjected to a
drying operation by supply of thermal energy.
16. The method according to claim 14, wherein the anticorrosion
coating has a thickness of the dry film of between 3 .mu.m (11
g/m.sup.2) and 30 .mu.m (110 g/m.sup.2).
17. A coated metallic substrate comprising an anticorrosion coating
formed from a coating composition including in the following
proportions (percentages by weight): at least one of an organic
titanate and an organic zirconate in an amount from 0.3 to 24%, a
particulate metal or a mixture of particulate metals in an amount
from 10 to 40%, a silane-based binder in an amount from 1 to 25%,
and water in an amount sufficient to produce 100%, wherein the sum
of the organic titanate and/or zirconate and of the silane-based
binder is between 5 and 25%.
18. An aqueous composition of C.sub.1-C.sub.8 tetraalkyl titanate,
adapted for use in a coating composition for a metallic substrate
in aqueous dispersion, in the following proportions (percentages by
weight): water-soluble organic solvent in an amount from 0 to 20%;
silane-based binder in an amount from 20 to 50%, the silane having
at least one hydrolysable hydroxyl function; at least one of
C.sub.1-C.sub.8 tetraalkyl titanate and zirconate in an amount from
5 to 25%, compatible in organic phase; and water in an amount
sufficient to produce 100%.
19. The composition according to claim 18, wherein the
water-soluble organic solvent is selected from the group consisting
of glycolic solvents, alcohols, ketones, and mixtures thereof.
20. The composition according to claim 18, wherein the hydrolysable
hydroxyl function is a C.sub.1-C.sub.4 alkoxy radical.
21. The composition according to claim 18, wherein the silane
includes an epoxy function.
22. The composition according to claim 21, wherein the silane is
selected from the group consisting of di- or trimethoxysilane with
an epoxy function, di- or triethoxysilane with an epoxy function,
and mixtures thereof.
23. The composition according to claim 18, wherein the
C.sub.1-C.sub.8 tetraalkyl titanate is selected from the group
consisting of tetraethyl titanate, tetra-n-butyl titanate, octylene
glycol titanate and mixtures thereof.
24. (canceled)
25. The composition according to claim 3 wherein the
C.sub.1-C.sub.8 tetraalkyl titanates are selected from the group
consisting of tetraethyl titanate, tetra-n-butyl titanate, octylene
glycol titanate, and combinations thereof.
26. The composition according to claim 3 wherein the
C.sub.1-C.sub.8 tetraalkyl zirconates are selected from the group
consisting of tetra-n-propyl zirconate, tetra-n-butyl zirconate,
and combinations thereof.
27. The composition according to claim 4 wherein the chelated
organic titanates are triethanolamine titanates.
28. The composition according to claim 4 wherein the chelated
organic zirconates are triethanolamine zirconates.
29. The composition according to claim 5 wherein the alloys include
metals selected from the group consisting of manganese, magnesium,
tin, and combinations thereof.
30. The composition according to claim 5 wherein the alloys include
a eutectic alloy of zinc and aluminium and a trace of rare earth
elements.
31. The composition according to claim 6 wherein the hydrolysable
hydroxyl function is a C.sub.1-C.sub.4 alkoxyl radical.
32. The composition according to claim 8 wherein the
trimethoxysilane is selected from the group consisting of
gamma-glycidoxypropyltrimethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and mixtures
thereof.
33. The composition according to claim 10 wherein the glycolic
solvents are glycol ethers.
34. The composition according to claim 33 wherein the glycol ethers
are selected from the group consisting of diethylene glycol,
triethylene glycol, dipropylene glycol, propylene glycol methyl
ether, and mixtures thereof.
35. The composition according to claim 10 wherein the glycolic
solvents are selected from the group consisting of propylene
glycol, polypropylene glycol, and mixtures thereof.
36. The composition according to claim 9 wherein the organic
solvent is 2,2,4-trimethyl-1, 3-pentanediol isobutyrate
(texanol).
37. The composition according to claim 12 wherein the reinforcing
agent is yttrium oxide Y.sub.2O.sub.3.
38. The composition according to claim 1 further comprising 0.2 to
4% by weight, with respect to the total weight of the composition,
of a corrosion inhibitor pigment.
39. The composition according to claim 38 wherein the corrosion
inhibitor pigment is aluminium triphosphate.
40. The composition according to claim 13 wherein the thickening
agent is present in an amount of 0.005 to 7% by weight with respect
to the total weight of the composition.
41. The composition according to claim 13 wherein the wetting agent
is present in an amount of 0.1 to 4% by weight with respect to the
total weight of the composition.
42. The method according to claim 14 wherein the baking operation
by supply of thermal energy includes at least one of convection,
infrared, and induction.
43. The method according to claim 14 wherein the baking operation
is performed at a temperature between 180.degree. C. and
350.degree. C.
44. The method according to claim 43 wherein the baking operation
is performed for approximately 10 to 60 minutes by convection or
infrared.
45. The method according to claim 43 wherein the baking operation
is performed for 30 seconds to 5 minutes by induction.
46. The anticorrosion coating formed by the method according to
claim 14.
47. The method according to claim 15 wherein the drying operation
by supply of thermal energy includes at least one of convection,
infrared, and induction.
48. The method according to claim 47 wherein the drying operation
is performed at a temperature between 30.degree. C. and 250.degree.
C. by convection.
49. The method according to claim 47 wherein the drying operation
is performed for approximately 10 to 30 minutes on a line.
50. The method according to claim 47 wherein the drying operation
is performed for 30 seconds to 5 minutes by induction.
51. The anticorrosion coating formed by the method according to
claim 15.
52. The method according to claim 16 wherein the thickness is
between 4 .mu.m (15 g/m.sup.2) and 12 .mu.m (45 g/m.sup.2).
53. The method according to claim 52 wherein the thickness is
between 5 .mu.m (18 g/m.sup.2) and 10 .mu.m (40 g/m.sup.2).
54. The anticorrosion coating formed by the method of claim 16.
55. The method according to claim 15 wherein the anticorrosion
coating has a thickness of the dry film of between 3 .mu.m (11
g/m.sup.2) and 30 .mu.m (110 g/m.sup.2).
56. The method according to claim 55 wherein the thickness is
between 4 .mu.m (15 g/m.sup.2) and 12 .mu.m (45 g/m.sup.2).
57. The method according to claim 56 wherein the thickness is
between 5 .mu.m (18 g/m.sup.2) and 10 .mu.m (40 g/m.sup.2).
58. The anticorrosion coating formed by the method of claim 55.
59. The metallic substrate of claim 17 wherein the metallic
substrate is selected from the group consisting of steel,
cast-iron, and aluminium.
60. The metallic substrate of claim 59 wherein the steel is zinc
coated.
61. The composition of claim 19 wherein the glycolic solvents
include glycol ethers.
62. The composition of claim 61 wherein the glycol ethers are
selected from the group consisting of diethylene glycol,
triethylene glycol, dipropylene glycol, and mixtures thereof.
63. The composition of claim 19 wherein the glycolic solvents
include propylene glycol, propylene glycol methyl ether, and
mixtures thereof.
64. The composition according to claim 19 wherein the hydrolysable
hydroxyl function is a C.sub.1-C.sub.4 alkoxyl radical.
65. The composition according to claim 22 wherein the
trimethoxysilane is selected from the group consisting of
gamma-glycidoxypropyltrimethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and mixtures
thereof.
66. The composition according to claim 18 wherein the
C.sub.1-C.sub.8 tetraalkyl zirconate is selected from the group
consisting of tetra-n-propyl zirconate, tetra-n-butyl zirconate,
and mixtures thereof.
67. A method for pretreating a substrate prior to receiving an
adhesive or coating, the method comprising: providing a composition
comprising in the following proportions (percentages by weight):
water-soluble organic solvent in an amount from 0 to 20%,
silane-based binder in an amount from 20 to 50% the silane having
at least one hydrolysable hydroxyl function, at least one of
C.sub.1-C.sub.8 tetraalkyl titanate and zirconate in an amount from
5 to 25% compatible in organic phase, and water in an amount
sufficient to produce 100%; applying a coating of the composition
to the substrate, to thereby pretreat the substrate.
68. A method for sealing a substrate or coated substrate, the
method comprising: providing a substrate or coated substrate;
providing a composition comprising in the following proportions
(percentages by weight): water-soluble organic solvent in an amount
from 0 to 20%, silane-based binder in an amount from 20 to 50% the
silane having at least one hydrolysable hydroxyl function, at least
one of C.sub.1-C.sub.8 tetraalkyl titanate and zirconate in an
amount from 5 to 25% compatible in organic phase, and water in an
amount sufficient to produce 100%; applying a coating of the
composition on the substrate, to thereby seal the substrate or
coated substrate.
69. A method for passivating a substrate of steel, zinc, aluminium,
or steel having a zinc-based coating, the method comprising:
providing a substrate selected from the group consisting of steel,
zinc, aluminium, and steel having a zinc-based coating; providing a
composition comprising in the following proportions (percentages by
weight): water-soluble organic solvent in an amount from 0 to 20%,
silane-based binder in an amount from 20 to 50% the silane having
at least one hydrolysable hydroxyl function, at least one of
C.sub.1-C.sub.8 tetraalkyl titanate and zirconate in an amount from
5 to 25% compatible in organic phase, and water in an amount
sufficient to produce 100%; applying a coating of the composition
on the substrate, thereby -passivating the substrate.
70. A method for improving the adhesion of coatings or adhesives in
aqueous phase, the method comprising: forming a composition
comprising in the following proportions (percentages by weight):
water-soluble organic solvent in an amount from 0 to 20%,
silane-based binder in an amount from 20 to 50% the silane having
at least one hydrolysable hydroxyl function, at least one of
C.sub.1-C.sub.8 tetraalkyl titanate and zirconate in an amount from
5 to 25% compatible in organic phase, and water in an amount
sufficient to produce 100%; adding the composition to a coating or
adhesive to thereby improve the resulting adhesion of the coating
or adhesive.
Description
[0001] The present invention relates to an anticorrosion coating
composition for metal parts, which is based on particulate metal in
aqueous dispersion comprising an organic titanate or zirconate
compatible in aqueous phase or in organic phase, optionally a
silane-based binder, and water.
[0002] In the sense of the present invention, the expressions
"titanate(s) compatible in organic phase" and "zirconate(s)
compatible in organic phase" are understood as meaning every
organic titanate and zirconate not compatible with water, that is
to say not soluble in an aqueous composition and which in addition
is sensitive to moisture and to water (hydrolysis reaction).
[0003] In the sense of the present invention, the expressions
"titanate(s) compatible in aqueous phase" and "zirconate(s)
compatible in aqueous phase" are understood as meaning every
organic titanate and zirconate compatible with water, that is to
say soluble or emulsifiable or dispersible in an aqueous
composition. These are generally organic titanates and organic
zirconates which have been stabilized by chelation. They are
likewise named "chelated (organic) titanate(s)" and "chelated
(organic) zirconate(s)".
[0004] The organic titanates, as well as the organic zirconates,
compatible in organic phase can be used in anhydrous compositions
as catalysts, reticulating agents, surface-treatment agents,
adhesion promoters or anticorrosion agents. However, these organic
titanates, as well as the organic zirconates, have the disadvantage
of being very sensitive to water and to moisture inasmuch as they
are hydrolysed very rapidly. For example, in the case of the
hydrolysis of tetra-n-butyl titanate, the following reactions
occur: [0005] 1) conversion of the organic titanate to hydrated
titanium oxide Ti(OH).sub.4:
Ti(OC.sub.4H.sub.9).sub.4+4H.sub.2O.fwdarw.Ti(OH).sub.4+4C.sub.4H.sub.9OH
[0006] 2) then, formation of titanium dioxide TiO.sub.2:
Ti(OH).sub.4.fwdarw.TiO.sub.2+2H.sub.2O
[0007] In order to avoid the formation of titanium dioxide, the
titanates and zirconates compatible in organic phase must thus be
employed under rigorously anhydrous conditions. Consequently, the
preparation of anhydrous compositions comprising a titanate or a
zirconate compatible in organic phase is accompanied by very
constraining handling precautions if it is wished to avoid the
hydrolysis of the organic titanate to titanium dioxide on contact
with air, moisture or traces of water.
[0008] The moisture resistance of titanates or zirconates
compatible in organic phase can be improved by substituting two
alkoxy groups by chelating agents. These chelating agents contain
functional groups containing oxygen or nitrogen atoms which happen
to stabilize the organic titanate or zirconate. These organic
titanates or zirconates in chelated form can likewise be soluble in
water, preferably in the presence of a weak acid of the acetic acid
type. For example, the patent U.S. Pat. No. 4,495,156 describes
titanates in aqueous chelated form (TYZOR AA which is a titanate
compatible in organic phase, TYZOR LA and TYZOR TE which are
titanates compatible in aqueous phase) which allow the adhesion to
a substrate of a composition comprising them to be improved.
[0009] The hydrolysis rate of the organic titanates and zirconates
depends on the size and the complexity of the alkyl group (the more
the size of the alkyl group increases, the more the hydrolysis rate
decreases). This is the reason why the organic titanates and
zirconates in chelated form are less sensitive to hydrolysis than
the tetraalkyl titanates or the tetra-alkyl zirconates.
[0010] The patent U.S. Pat. No. 4,224,213 describes coating
compositions comprising a short-chain alkyl silicate of formula
Si(OR).sub.4, a short-chain alkyl titanate or zirconate and zinc
powder. This coating composition is reticulated by reaction of the
silicate and the titanate with moisture from the air. The examples
of this patent teach that the addition of silicate allows the
moisture resistance of organic titanates to be improved. This
coating composition is an organic composition which does not
contain any water. The silicate, contrary to the silane, does not
allow the adhesion of a composition comprising it to a
substrate.
[0011] The patent EP 0 808 883 describes an aqueous coating
composition based on particulate metal, free from chromium,
intended to be applied to a substrate. This composition, once
applied to the substrate, undergoes hardening in heat in order to
provide the said substrate with protection against corrosion. In
order to increase the corrosion resistance of this coated
substrate, the coated substrate can optionally be coated with a
supplementary layer comprising, for example, a silica material.
[0012] Surprisingly, the inventors have succeeded in incorporating
into an aqueous composition organic titanates and/or organic
zirconates, whether they are in chelated or non-chelated form and
compatible or not compatible in aqueous phase. They have likewise
discovered that the application to a metallic substrate of an
aqueous coating composition based on particulate metal comprising
organic titanates and/or organic zirconates allows the resistance
to corrosion of the substrate to be improved. The anticorrosion
results being sufficient, a substrate coated by such a composition
does not need any supplementary layer of anticorrosion coating. In
addition, a coating is obtained whose flexibility and resistance to
shocks is of very good quality, which is particularly advantageous
in the case of anticorrosion coating of screws.
[0013] The present invention relates to an anticorrosion coating
composition of metal parts based on particulate metal in aqueous
dispersion comprising, in the following proportions (percentages by
mass): [0014] an organic titanate and/or zirconate : 0.3 to 24%;
[0015] a particulate metal or a mixture of particulate metals 10 to
40%; [0016] a silane-based binder : 1 to 25%; [0017] water : q.s.p.
100%; with the condition that the sum of the organic titanate
and/or the organic zirconate and of the silane-based binder is
between 5 and 25%.
[0018] The composition advantageously comprises 0.5 to 19% by
weight, with respect to the total weight of the composition, of
organic titanate and/or zirconate and 1 to 20% by weight, with
respect to the total weight of the composition, of silane-based
binder, on condition that the sum of organic titanate and/or
zirconate and silane-based binder is between 7 and 20% by weight,
with respect to the total weight of the composition.
[0019] The organic titanates can be chosen from the group
constituted by the organic titanates compatible in organic phase
and the organic titanates compatible in aqueous phase.
[0020] The titanates compatible in organic phase are advantageously
C.sub.1-C.sub.8 tetraalkyl titanates which can be represented by
the following formula (I'): ##STR1## in which R1, R2, R3 and R4
independently represent an optionally substituted C.sub.1-C.sub.8
alkyl radical. The C.sub.1-C.sub.8 tetraalkyl titanate is
advantageously chosen from the group comprising tetraethyl titanate
(TET, Ti(OC.sub.2H.sub.5).sub.4), tetra-n-butyl titanate
(T.sub.nBT, Ti(OC.sub.4H.sub.9).sub.4) and octylene glycol titanate
(OGT, Ti(O.sub.2C.sub.8H.sub.17).sub.4).
[0021] The organic titanates compatible in organic phase can
likewise be organic titanates in chelated form not compatible with
water. As examples of organic titanates in chelated form not
compatible with water (compatible in organic phase) it is
especially possible to cite those marketed by Dupont de Nemours
under the name TYZOR.RTM. AA (titanium acetylacetonate) or
TYZOR.RTM. DC (diisopropoxy bisethylacetoacetato titanate).
[0022] The titanates compatible in aqueous phase are advantageously
chelated titanates, which can be represented by the following
general formula (II'): ##STR2## in which R and R' independently of
one another represent an optionally substituted C.sub.1-C.sub.8
alkyl radical, X and X' independently represent a functional group
comprising an oxygen or nitrogen atom, and Y and Y' independently
represent a hydrocarbon chain having 1 to 4 carbon atoms. X and X'
advantageously represent an amino or lactate radical.
[0023] The organic titanate in chelated form compatible in aqueous
phase is advantageously chosen from the group constituted by the
triethanolamine titanates (TYZOR.RTM. TE and TEP marketed by Dupont
de Nemours). As an example of organic titanates in chelated form
compatible in aqueous phase, it is likewise possible to cite those
marketed by Dupont de Nemours under the name TYZOR.RTM. TA
(alkanolamine titanate in chelated form) and TYZOR.RTM. LA (chelate
of titanate and lactic acid).
[0024] The organic zirconate can be chosen from the group
constituted by the zirconates compatible in organic phase and the
zirconates compatible in aqueous phase.
[0025] The organic zirconates compatible in organic phase are
advantageously C.sub.1-C.sub.10 tetraalkyl zirconates, which can be
represented by the following formula (I): ##STR3## in which R1, R2,
R3 and R4 independently represent an optionally substituted
C.sub.1-C.sub.10 alkyl radical. The C.sub.1-C.sub.10 tetraalkyl
zirconate is advantageously chosen from the group constituted by
tetra-n-propyl zirconate and tetra-n- butyl zirconate.
[0026] The organic zirconates compatible in organic phase can
likewise be organic zirconates in chelated form not compatible with
water. As an example of an organic zirconate in chelated form not
compatible with water (compatible in organic phase), it is
especially possible to cite those marketed by Dupont de Nemours
under the name TYZOR.RTM. ZEC (chelated diethyl citrate
zirconate).
[0027] The organic zirconates compatible in aqueous phase are
advantageously chelated zirconates which can be represented by the
following general formula (II): ##STR4## in which R and R'
independently of one another represent an optionally substituted
C.sub.1-C.sub.10 alkyl radical, X and X' independently represent a
functional group comprising an oxygen or nitrogen atom, and Y and
Y' independently represent a hydrocarbon chain having 1 to 4 carbon
atoms. X and X' advantageously represent an amino radical.
[0028] The chelated organic zirconate can advantageously be
triethanolamine zirconate (TYZOR.RTM. TEAZ marketed by Dupont de
Nemours). As an example of an organic zirconate in chelated form
compatible in aqueous phase, it is likewise possible to cite that
marketed by Dupont de Nemours under the name TYZOR.RTM. LAZ
(chelate of zirconate and lactic acid).
[0029] The particulate metal of the coating composition can be
chosen from the group constituted by the metallic pigments such as
aluminium, manganese, nickel, titanium, stainless steel, zinc,
their alloys, as well as their mixtures. The particulate metal is
advantageously chosen from zinc and aluminium, as well as their
alloys and their mixtures or their alloys with manganese,
magnesium, tin or Galfan. The particulate metal present in the
composition is advantageously in powder form, different homogeneous
or heterogeneous geometric structures, especially spherical,
lamellar, lenticular forms or other specific forms. The particulate
metal advantageously has a particle size of less than 100 .mu.m,
even more advantageously less than 40 .mu.m. When the particulate
metal is an alloy or a mixture of zinc and aluminium, the aluminium
can optionally be present in very small quantities, for example 1
to 5% by weight of the particulate metal, while at the same time
nevertheless providing a coating of shiny appearance. Customarily,
the aluminium represents at least 10% by weight of the particulate
metal, thus the weight ratio of the aluminium to the zinc is of the
order of 1:9. On the other hand, for reasons of economy, the
aluminium does not represent more than approximately 50% by weight
of the total zinc and aluminium, so that the weight ratio of the
aluminium to the zinc can reach 1:1. The content of particulate
metal of the coating composition will not exceed approximately 40%
by weight of the total weight of the composition in order to
maintain the best coating appearance and will customarily represent
at least 10% by weight in order to obtain a shiny coating
appearance.
[0030] The metal can contain in minor quantity one or more
solvents, for example dipropylene glycol and/or white spirit,
especially when the metal has been prepared in lamellar form. The
particulate metals containing solvents are customarily used in the
form of pastes, which can be used directly with other ingredients
of the composition.
[0031] However, the particulate metals can likewise be used in a
dry form in the coating composition.
[0032] The said silane-based binder advantageously comprises a
silane carrying at least one hydrolysable function in hydroxyl
function chosen from a C.sub.1-C.sub.4, preferably C.sub.1-C.sub.2,
alkoxy radical. The silane advantageously carries three
hydrolysable functions in hydroxyl function, preferably identical.
The silane can additionally carry an epoxy (oxirane) function,
which favours the reticulation and adhesion to the substrate.
"Hydrolysable function in hydroxyl function" is understood as
meaning any chemical function capable of reacting with water in
order to be converted into a hydroxyl function --OH.
[0033] The silanes, in the compositions of the present invention,
serve as binding agents. They likewise allow the coating bath to be
stabilized against a harmful autogenous reaction. The silane seems
to bind and passivate the particulate metal, so that the stability
of the bath of the coating composition is improved. In addition, it
allows the adhesion of the coating and its resistance to corrosion
to be improved. The silane advantageously represents 3 to 20% by
weight of the total weight of the composition.
[0034] The silane is advantageously easily dispersed in the aqueous
medium and is, preferably, soluble in such a medium. The silane
used is advantageously a silane with an epoxy function chosen from
di- or trimethoxysilane with an epoxy function and di- or
triethoxysilane with an epoxy function, as well as their mixtures,
in particular like
beta-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane,
4-(trimethoxysilyl)butane-1,2-epoxide or
gamma-glycidoxypropyltrimethoxysilane.
[0035] If the organic titanate and/or zirconate used is an organic
titanate and/or zirconate compatible in aqueous phase, the silane
is advantageously introduced in quantities such that the
proportions by mass, in the final composition, of organic titanate
and/or zirconate compatible in aqueous phase:silane are between
95:5 and 5:95.
[0036] The anticorrosion composition can be prepared by mixing an
organic phase, especially comprising the silane and the particulate
metal, with an aqueous phase, especially comprising water and the
silane. The organic titanate and/or zirconate compatible in aqueous
phase can be introduced either into the aqueous phase or into the
organic phase.
[0037] When the organic titanate and/or zirconate compatible in
aqueous phase is introduced into the organic phase, it is possible
to substitute the silane, normally present in the organic phase, by
this organic titanate and/or zirconate.
[0038] The proportions by mass, expressed in dry parts, of organic
titanate and/or zirconate and of silane are advantageously between
1:19 and 2:1, more advantageously between 1:16 and 1:8.
[0039] When the organic titanate and/or zirconate compatible in
aqueous phase is introduced into the aqueous phase, it is
advantageously first co-hydrolysed with the silane, normally
present in the aqueous phase. The mass proportions of organic
titanate and/or zirconate and of silane during the co-hydrolysis
are advantageously between 0.12 and 0.36, expressed in dry parts.
The optimal conditions for the co-hydrolysis are obtained for a
ratio by mass of 0.24 titanate and/or zirconate for 1 silane, the
ratios being expressed in dry parts.
[0040] In order to co-hydrolyse the organic titanate and/or
zirconate and the silane, the organic titanate and/or zirconate is
introduced into the silane, in an appropriate ratio, then they are
co-hydrolysed by addition of 200 to 500% of water. It would appear
that the duration of the co-hydrolysis reaction, that is to say the
waiting time which follows the addition of the water, for example
30 or 90 min, does not have any influence on the properties of the
co-hydrolysate obtained. If, instead of co-hydrolysing the silane
and the organic titanate and/or zirconate compatible in aqueous
phase, they are each hydrolysed separately, less satisfactory
results are obtained in terms of product stability.
[0041] The addition of organic titanate and/or zirconate compatible
in aqueous phase in the aqueous phase of the anticorrosion
composition improves the anticorrosion properties of this
composition more than if this titanate and/or zirconate had been
added in the organic phase.
[0042] If the organic titanate and/or zirconate used is a titanate
and/or zirconate compatible in organic phase, advantageously a
C.sub.1-C.sub.8 tetraalkyl titanate and/or zirconate, the silane is
advantageously introduced in quantities such that the proportions
by mass, in the final composition, of titanate and/or zirconate
compatible in organic phase/silane are between 60/40 and 5/95,
advantageously between 50/50 and 10/90.
[0043] The liquid medium of the coating composition is virtually
always water or a combination of water and organic solvent. Other
solvents can optionally be used but, preferably, only in very small
quantities. Typically, the composition comprises 28 to 65% by
weight of water, with respect to the total weight of the
composition.
[0044] According to an advantageous embodiment of the invention,
the coating composition additionally comprises 1 to 30% by weight
of organic solvent or of a mixture of organic solvents, with
respect to the total weight of the composition. The organic
solvents are advantageously chosen from the group constituted by
the glycolic solvents such as the glycol ethers, in particular
diethylene glycol, triethylene glycol and dipropylene glycol, the
acetates, propylene glycol, polypropylene glycol, nitropropane, the
alcohols, the ketones, propylene glycol methyl ether,
2,2,4-trimethyl-1,3-pentanediol isobutyrate (texanol), white
spirit, as well as their mixtures.
[0045] Dipropylene glycol is particularly advantageous, especially
for reasons of economy and of protection of the environment. The
quantity of solvents is advantageously lower than 25% by weight,
even more advantageously lower than 16% by weight, with respect to
the total weight of the composition. When the metallic particles
have been prepared in lamellar form in a solvent, the particulate
metal resulting can be in the form of paste. It can then form a
part of the organic solvent of the composition according to the
invention.
[0046] According to an advantageous embodiment of the invention,
the coating composition additionally comprises 0.1 to 7% by weight
of molybdenum oxide, with respect to the total weight of the
composition. The presence of molybdenum oxide MoO.sub.3 in the
anticorrosion coating composition allows control of the sacrificial
protection exerted by the particulate metal in suspension in the
composition to be improved. The molybdenum oxide MoO.sub.3 is
preferably used in an essentially pure orthorhombic crystalline
form having a content of molybdenum of greater than approximately
60% by mass. Advantageously, the molybdenum oxide MoO.sub.3 will be
used in the anticorrosion compositions in the form of particles of
dimensions of between 5 and 200 .mu.m.
[0047] According to an advantageous embodiment of the invention,
the coating composition additionally comprises 0.5 to 10% by weight
of a reinforcing agent of the anticorrosion properties of the
composition chosen from the group constituted by yttrium,
zirconium, lanthanum, cerium, praseodymium, in the form of oxides
or of salts. The said reinforcing agent of the anticorrosion
properties of the composition is advantageously yttrium oxide
Y.sub.2O.sub.3 or cerium chloride. The said reinforcing agent of
the anticorrosion properties of the composition can advantageously
be combined with the abovementioned molybdenum oxide, in a mass
ratio 0.25<reinforcing agent of the anticorrosion properties:
MoO.sub.3<20, advantageously 0.5<reinforcing agent of the
anticorrosion properties: MoO.sub.3<16, even more advantageously
0.5<reinforcing agent of the anticorrosion properties:
MoO.sub.3<14.
[0048] According to an advantageous embodiment, the coating
composition additionally comprises a corrosion inhibitor pigment or
corrosion inhibitor pigments such as the tri- or polyphosphate of
aluminium, the phosphates, the molybdates, the silicates and
borates of zinc, strontium, calcium, barium and their mixtures, at
levels of the order of 0.2 to 4% by weight, with respect to the
total weight of the coating composition.
[0049] The coating composition according to the invention can
additionally comprise a thickening agent. The thickening agent is
advantageously chosen from the group constituted by the cellulosic
derivatives such as hydroxymethylcellulose, hydroxyethylcellulose,
hydroxy-propylcellulose, cellulose acetobutyrate, xanthan gum, the
associative thickeners of polyurethane or acrylic type, the
silicates such as the optionally treated silicates of magnesium
and/or of lithium or the organophilic clays as well as their
mixtures. The content of thickening agent is advantageously lower
than 7% by weight with respect to the total weight of the
composition, advantageously between 0.005 and 7% by weight with
respect to the total weight of the composition.
[0050] The coating composition according to the invention can
likewise comprise a wetting agent, in a content advantageously
lower than 4% by weight, more advantageously between 0.1 and 4% by
weight, with respect to the total weight of the composition.
[0051] The composition according to the invention can also comprise
a pH stabilizer such as boric acid, metaboric acid, tetraboric acid
and boron oxide or boron salts. The composition can comprise, with
respect to the total weight of the composition, 0.1 to 10% by
weight, advantageously 0.2 to 5% by weight and even more
advantageously 0.4 to 0.8% by weight, of pH stabilizer.
[0052] The composition can likewise comprise a pH modifier,
generally chosen from the oxides and the hydroxides of alkali
metals, advantageously lithium and sodium, the oxides and the
hydroxides of metals belonging to groups IIA and IIB of the
Periodic Table, such as the compounds of strontium, calcium,
barium, magnesium and zinc. The pH modifier can likewise be a
carbonate or a nitrate of the abovementioned metals.
[0053] The composition according to the invention can likewise
comprise phosphates, substituents containing phosphorus, such as
ferrophosphate (pigment), non-organic salts, in quantities lower
than 2% by weight with respect to the weight of the
composition.
[0054] The composition according to the invention is advantageously
free from chromium VI. The composition can, however, contain
chromium in soluble or non-soluble form such as, for example,
metallic chromium or chromium of oxidation state III.
[0055] The composition has good stability on storage, confirming
the protective role of the silane towards a harmful reaction of the
particulate metal with other ingredients of the composition. The
silane likewise allows organic titanate to be stabilized.
[0056] The present invention likewise relates to the coating
obtained by application of the coating composition according to the
invention to a substrate, advantageously by spraying,
soaking-draining or soaking-centrifugation, the coating layer then
being subjected to a baking operation, preferably at a temperature
of between 180.degree. C. and 350.degree. C., for approximately 10
to 60 minutes, by supply of thermal energy, such as by convection
or infrared, or for approximately 30 seconds to 5 minutes by
induction.
[0057] According to an advantageous embodiment, the anticorrosion
coating will result from an application operation involving, prior
to a baking operation, a drying operation of the coated metallic
parts, by supply of thermal energy, such as by convection,
infra-red or induction, at a temperature of between 30 and
250.degree. C., advantageously of the order of 70.degree. C., in
convection or in infrared for 10 to 30 minutes on line or for
approximately 30 seconds to 5 minutes by induction. Before coating,
it is judicious in the majority of cases to eliminate the foreign
matter from the surface of the substrate, especially by cleaning
and careful degreasing. Under these conditions, the thickness of
the dry coating film thus applied is between 3 .mu.m (11 g/m.sup.2)
and 30 .mu.m (110 g/m.sup.2) and preferably between 4 .mu.m (15
g/m.sup.2) and 12 .mu.m (45 g/m.sup.2), more particularly between 5
.mu.m (18 g/m.sup.2) and 10 .mu.m (40 g/m.sup.2).
[0058] The present invention also extends to the metallic
substrate, preferably of steel or steel coated with zinc or with a
base layer of zinc deposited by different application methods
including mechanical deposition, to cast iron and aluminium,
provided with an anticorrosion coating according to the invention
applied with the aid of the abovementioned compositions.
[0059] The metallic substrate can be previously treated, for
example by a treatment with chromate or with phosphate. Thus, the
substrate can be pretreated in order to have, for example, a
phosphate coating of iron in a quantity of 0.1 to 1 g/m.sup.2 or a
phosphate coating of zinc in a quantity of 1.5 to 4 g/m.sup.2.
[0060] The present invention likewise relates to an aqueous
composition of C.sub.1-C.sub.8 tetraalkyl titanate and/or of
C.sub.1-C.sub.8 tetraalkyl zirconate, intended for the preparation
of a coating composition for a metallic substrate in aqueous
dispersion, prepared from a water-soluble organic solvent, a binder
containing a silane carrying at least one hydrolysable function in
hydroxyl function, a C.sub.1-C.sub.8 tetraalkyl titanate and/or
zirconate and water, in the following proportions (percentages by
mass): [0061] water-soluble organic solvent : 0 to 20% [0062]
silane-based binder : 20 to 50% [0063] C.sub.1-C.sub.8 tetraalkyl
titanate and/or zirconate : 5 to 25% [0064] water : 40 to 70%
[0065] In the context of the present invention, that is to say when
the silane is found in the presence of C.sub.1-C.sub.8 tetraalkyl
titanate and/or zirconate, it would appear that the silane, in
hydrolysed form before condensation, is capable of reacting with
the abovementioned hydrated titanium oxide and/or zirconate in
order to give a partially stable polymeric chain containing silicon
and titanium and/or zirconate atoms. The silane then appears
capable of stabilizing the C.sub.1-C.sub.8 tetraalkyl titanate
and/or zirconate. The chemical reactions could be written as
follows:
[0066] (1) Hydrolysis of the silane:
R--Si(OR').sub.3+3H.sub.2OR--Si(OH).sub.3+3R'OH
[0067] (2) Conversion of the organic titanate or zirconate to
hydrated titanium or zirconium oxide:
X--(OR'').sub.4+4H.sub.2O.revreaction.X(OH).sub.4+4R''OH
[0068] (3) Reaction between the hydrated titanium or zirconium
oxide and the hydrolysed silane:
2R--Si(OH).sub.3+X(OH).sub.4.revreaction.X(OH).sub.2.2[R--SiO(OH).sub.2]
[0069] The silane and the organic titanate or zirconate thus
associate in order to form the following partial polymeric chain:
X(OH).sub.2.2[R--SiO(OH).sub.2]
[0070] The reaction can continue and lead to the formation of a
polymeric chain of the following formula (III): ##STR5## in which X
represents Ti or Zr.
[0071] The water-soluble organic solvent is advantageously chosen
from the group constituted by the glycolic solvents such as the
glycol ethers, in particular diethylene glycol, triethylene glycol
and dipropylene glycol, the acetates, propylene glycol, the
alcohols, the ketones, propylene glycol ether, as well as their
mixtures.
[0072] The silane carrying at least one hydrolysable function in
hydroxyl function contained in the binder is advantageously chosen
from a C.sub.1-C.sub.4, even more advantageously C.sub.1-C.sub.2,
alkoxy radical. In addition, this silane advantageously carries an
epoxy function. The said silane is preferably chosen from di- or
trimethoxysilane with an epoxy function and di- or triethoxysilane
with an epoxy function, as well as their mixtures, in particular
gamma-glycidoxypropyl-trimethoxysilane or
beta-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane.
[0073] The C.sub.1-C.sub.8 tetraalkyl titanate is advantageously
chosen from the group comprising tetra-ethyl titanate (TET),
tetra-n-butyl titanate (T.sub.nBT) and octyleneglycol titanate
(OGT) and the C.sub.1-C.sub.8 tetraalkyl zirconate is chosen from
the group comprising tetra-n-propyl zirconate and tetra-n-butyl
zirconate. In the aqueous composition, the ratio by mass of
C.sub.1-C.sub.8 tetraalkyl titanate and/or zirconate with respect
to the silane is from 60/40 maximum, advantageously to 50/50
maximum, advantageously to 40/60 maximum.
[0074] The aqueous composition of C.sub.1-C.sub.8 tetraalkyl
titanate and/or C.sub.1-C.sub.8 tetraalkyl zirconate can be
prepared by mixing the silane-based binder, the said titanate or
zirconate and, if necessary, the said water-soluble organic
solvent, with a small quantity of water and then, by continuous
progressive addition, at a low rate, of the remaining quantity of
water.
[0075] In this stabilized form, the C.sub.1-C.sub.8 tetraalkyl
titanate and/or zirconate can, for example, then be introduced into
a coating composition for a metallic substrate in aqueous phase,
especially an anticorrosion coating composition based on
particulate metal in aqueous dispersion, while limiting the
formation of titanium dioxide.
[0076] The present invention finally relates to the use of the
aqueous composition of C.sub.1-C.sub.8 tetraalkyl titanate and/or
C.sub.1-C.sub.8 tetraalkyl zirconate defined above in pretreatment
for coatings or adhesives (polyurethane, acrylic, rubber . . . ).
This composition can also be used in posttreatment as a sealer
based on metallic particles. This composition can likewise be used
in passivation treatment for substrates based on steel, zinc,
aluminium or steel covered with a zinc-based coating. This
composition can finally be used in an additive in order to improve
the adhesion of the coatings or adhesives (polyurethane, acrylic,
rubber, . . . ) in aqueous phase.
[0077] The examples below show ways in which the present invention
can be employed, but do not limit the present invention in any
fashion.
Preparation of the Test Panels:
[0078] Unless indicated otherwise, the test panels are typically
stainless steel panels with a low carbon content, laminated in the
cold. They can be prepared first of all by immersion in a cleaning
solution. Then, the panels can be wiped with a cleaning pad and
then rinsed with water and again immersed in the cleaning solution.
After removal of the solution, the panels are rinsed with tap water
and dried.
Application of the Coating to the Test Panels and Weight of the
Coating:
[0079] The clean parts are coated, in a typical fashion, by dipping
then into the coating composition, by withdrawing and draining the
composition in excess of this, several times with a moderate
stirring action, and then by immediate baking or drying at ambient
temperature or pre-hardening at a moderate temperature until the
coating is dry to the touch and thus baked. The coating weights
(mg/cm.sup.2) are determined by comparative weighing before and
after coating.
[0080] Test of Resistance to Corrosion (ISO 9227) and
Estimation:
[0081] The resistance to corrosion of coated parts is measured by
means of the standard salt projection test (saline mist) for paints
and varnishes ISO 9227. In this test, the parts are placed in a
chamber maintained at a constant temperature where they are exposed
to a fine projection (mist) of a 5% saline solution during specific
periods of time, rinsed with water and dried. The extent of
corrosion of the parts tested can be expressed in the form of the
percentage of red rust.
EXAMPLE 1
Composition Based on Organic Titanate Compatible in Organic
Phase
[0082] TABLE-US-00001 TABLE 1 Constituent Quantity (g/kg) DPG
(dipropylene glycol) 170.60 R40.sup.5 13.00 R95.sup.6 14.00 Dry
aluminium.sup.2 25.00 Zinc paste.sup.1 245.00 Silane A-187.sup.3
90.00 Dehydran.sup.10 5.00 Sodium silicate.sup.4 8.00 Boric acid
7.50 Molybdenum oxide.sup.9 8.00 T.sub.nBT (tetra-n-butyl
titanate).sup.8 40.00 Kelzan.sup.7 0.65 Water 373.30 .sup.1Zinc in
the form of paste to approximately 92% in white spirit .sup.2Alu
Chromal VIII powder marketed by Eckart Werke
.sup.3.gamma.-glycidoxypropyltrimethoxysilane (Crompton)
.sup.4sodium silicate (Rhodia) .sup.5,6Ethoxylated nonylphenol of
R40 or of R95, supplier Oxiteno SA (Brazil) .sup.7Kelzan/Rhodopol
23 from Rhodia .sup.8supplier DuPont de Nemours .sup.9supplier
Lavollee .sup.10supplier Cognis SA
EXAMPLE 2
Composition Based on Organic Titanate Compatible in Organic
Phase
[0083] TABLE-US-00002 TABLE 2 a) composition: Constituent Quantity
(g/kg) DPG (dipropylene glycol) 175.60 R40 13.00 R95 14.00 Dry
aluminium 10.00 Zinc paste 260.00 Silane A-187 115.00 Silicate H300
10.00 Boric acid 9.50 Molybdenum oxide 10.00 T.sub.nBT
(tetra-n-butyl titanate) 60.00 Kelzan 0.65 Water 317.25
[0084] TABLE-US-00003 TABLE 3 b) Results of tests of resistance to
saline mist Duration of bath Density coating layer Resistance to
saline mist (days) (g/m.sup.2) (hours) 5 23.6 2064 10 19.8 1944 15
20.1 1752
EXAMPLE 3
Composition Based on Organic Titanate Compatible in Organic
Phase
[0085] TABLE-US-00004 TABLE 4 a) composition: Constituent Quantity
(g/kg) DPG (dipropylene glycol) 153.50 R40 13.00 R95 14.00 Dry
aluminium 10.00 Zinc paste 260.00 Silane A-187 95.00 Silicate H300
10.00 Boric acid 9.50 Molybdenum oxide 10.00 TET (tetraethylene
titanate) .sup.11 40.00 Kelzan 0.65 Water 379.35 .sup.11 supplied
by DuPont de Nemours
[0086] TABLE-US-00005 TABLE 5 b) Results of tests of resistance to
saline mist Duration of bath Density coating layer Resistance to
saline mist (days) (g/m.sup.2) (hours) 5 20.8 456 10 19.7 360
EXAMPLE 4
Process for Preparation of an Aqueous Composition of Tetrabutyl
Titanate, Organic Titanate Compatible in Organic Phase
[0087] The following reagents are mixed in order: [0088] a) 30.00 g
of DPG (dipropylene glycol) [0089] b) 50.00 g of silane A-187
[0090] c) 20.00 g of TBT (tetrabutyl titanate)
[0091] The solution obtained is allowed to stand for 24 hours. The
silane, introduced into the DPG before the T.sub.nBT, reacts with
the water optionally present in the DPG. An uncontrolled reaction
of the organic titanate with the water optionally present in the
DPG is thus avoided.
[0092] 100.00 g of water (=100.00 ml) are added respecting the
following procedure: [0093] i) add 0.125 ml of water dropwise and
then allow the solution to stand for 10 minutes; [0094] ii) repeat
step i) 5 times; [0095] iii) add the remaining quantity of water at
a rate of 0.25 ml of water/minute/3 pulses, or approximately 0.083
ml of water every 20 seconds.
[0096] An aqueous composition of colourless organic titanate is
obtained. Small crystals can appear; it is assumed that these are
silica crystals.
[0097] The total duration of the preparation of the aqueous
composition of organic titanate is approximately 7 h 30 min.
[0098] The aqueous composition of organic titanate is allowed to
stand for at least 24 hours before optionally being introduced into
a composition of anticorrosion coating.
EXAMPLE 5
Process for Preparation of an Aqueous Composition of Organic
Titanate Compatible in Organic Phase
[0099] The process proceeds in the same fashion as in example 4
except that the quantity of T.sub.nBT introduced is 30.00 g. An
aqueous composition of colourless or sometimes slightly yellow
organic titanate is obtained.
EXAMPLE 6
Process for Preparation of an Aqueous Composition of Organic
Titanate Compatible in Organic Phase
[0100] The process proceeds in the same fashion as in example 4
except that the quantity of T.sub.nBT introduced is 40.00 g. An
aqueous composition of colourless or sometimes slightly yellow
organic titanate is obtained.
EXAMPLE 7
Process for Preparation of an Aqueous Composition of Organic
Titanate Compatible in Organic Phase
[0101] The process proceeds in the same fashion as in example 4
except that the quantity of T.sub.nBT introduced is 40.00 g and the
quantity of silane A 187 introduced is 70.00 g. An aqueous
composition of colourless or sometimes slightly yellow organic
titanate is obtained.
EXAMPLE 8
Corrosion Resistance of a Coating Composition According to the
Invention Based on Organic Titanate Compatible in Organic Phase
[0102] The aqueous composition of organic titanate obtained in
example 6 is introduced into an anticorrosion coating composition.
Table 6 below indicates the formulation of the composition thus
obtained and that of an anticorrosion coating composition of the
prior art which do not contains organic titanate. TABLE-US-00006
TABLE 6 Composition according Composition of the to the invention A
(g/kg) prior art B (g/kg) DPG 160.60 160.60 Silane A 187 90.00
90.00 Water 383.30 421.10 Tetra-n-butyl titanate 40.00 -- Dry
aluminium lamellae 25.00 25.00 Zinc paste 245.00 245.00 Molybdenum
oxide 8.00 10.00 R40 13.00 13.00 R95 14.00 14.00 Dehydran 5.00 5.00
Sodium silicate 8.00 8.00 Boric acid 7.50 7.50 Kelzan 0.60 0.80
[0103] The characteristics of composition A are reported in table 7
below: TABLE-US-00007 TABLE 7 Duration of the den- % of bath
adhesion appearance pH sity solid viscosity 72 hours excellent very
good 7.7 1.35 36.1 54 s (23.degree. C.) 5 days excellent very good
7.9 1.36 37.0 64 s (23.degree. C.) 10 days excellent very good 8.1
1.39 38.3 70 s (26.degree. C.) 15 days excellent very good 7.9 1.40
40.0 83 s (26.degree. C.) 20 days excellent very good 7.8 1.42 41.9
121 s (25.degree. C.) 25 days excellent very good 8.1 1.39 39.4 90
s (24.degree. C.)
[0104] The resistance of the two compositions to the saline mist is
compared. The resistance values to the saline mist measured are
summarized in table 8 below. TABLE-US-00008 TABLE 8 Composition
according to the Composition of the prior art invention A B
Resistance to Resistance to Density coating saline mist Density
coating saline mist layer (g/m.sup.2) (hours) layer (g/m.sup.2)
(hours) 16 704 16 208 20 880 20 260 24 1056 24 312 28 1232 28 364
32 1408 32 416 36 1584 36 468
[0105] Satisfactory results for resistance to the saline mist are
thus observed for the coating composition according to the
invention. In fact, for a layer density of 24 g/m.sup.2, it is
possible to attain a duration of resistance to the saline mist of
greater than 1000 hours whereas for a composition without organic
titanate the duration of resistance to the saline mist is only 312
hours. The addition of organic titanate allows the corrosion
resistance of the coating to be at least tripled under these
conditions.
EXAMPLE 9
Composition Based on Organic Titanate Compatible in Organic
Phase
[0106] The addition of small quantities of organic titanate (10, 20
or 30 g/kg) allows the quantity of silane and of molybdenum oxide
to be introduced to be decreased, which allows a limitation of the
costs, while conserving good anticorrosion results.
[0107] In the following examples of compositions (table 9), the
quantity of silane is reduced to 44% by weight and the quantity of
molybdenum oxide is reduced to 20% by weight, with respect to the
quantities conventionally introduced into anticorrosion coating
compositions. TABLE-US-00009 TABLE 9 Composition Composition
Composition C (g/kg) D (g/kg) E (g/kg) DPG 160.60 160.60 160.60
Silane A 187 50.00 50.00 50.00 Water 453.20 443.20 433.20
Tetra-n-butyl titanate 10.00 20.00 30.00 Dry aluminium lamellae
25.00 25.00 25.00 Zinc paste 245.00 245.00 245.00 Molybdenum oxide
8.00 8.00 8.00 R40 13.00 13.00 13.00 R95 14.00 14.00 14.00 Dehydran
5.00 5.00 5.00 Sodium silicate 8.00 8.00 8.00 Boric acid 7.50 7.50
7.50 Kelzan 0.70 0.70 0.70
[0108] The values of resistance to the saline mist measured are
summarized in table 10 below. TABLE-US-00010 TABLE 10 Composition C
Composition D Composition E Weight of layer 21 22.5 20.5
(g/m.sup.2) Red rust (number of 170 310 430 hours)
EXAMPLE 10
Process of Introduction of Chelated Organic Titanates or
Zirconates, Compatible in Aqueous Phase, into an Aqueous
Phase--Co-Hydrolysis with the Silane
[0109] a) Titanates [0110] i) Preparation of the Aqueous Phase:
[0111] 10 parts by weight of TYZOR.RTM. TEP (supplied by DuPont de
Nemours, 60% dry extract) and 25 parts by weight of silane A-187
are mixed with magnetic stirring for one hour. 113 parts by weight
of water are then added rapidly and the magnetic stirring is
maintained for one hour.
[0112] This mixture is then introduced into an aqueous composition
constituted of 350 parts by weight of water, 8.8 parts by weight of
sodium silicate, 8.2 parts by weight of boric acid and 9 parts by
weight of molybdenum oxide.
[0113] ii) Composition of the Organic Phase: TABLE-US-00011 The
organic phase contains: dipropylene glycol 75 parts by weight
Remcopal N4 100.sup.12 14 parts by weight Remcopal N9 1001.sup.13
15.5 parts by weight Silane A 187 70 parts by weight Zinc paste 235
parts by weight Aluminium Stapa.sup.14 30 parts by weight Schwego
foam 8325.sup.15 5.5 parts by weight Yttrium oxide.sup.16 30 parts
by weight aerosil 380.sup.17 0.4 part by weight .sup.12wetting
agent of ethoxylated nonylphenol type (CECA) .sup.13wetting agent
of ethoxylated nonylphenol type (CECA) .sup.1480% Chromal VIII in
dipropylene glycol, marketed by Eckart Werke
.sup.15hydrocarbon-type antifoam (Schwegman) .sup.16Y.sub.2O.sub.3
of purity equal to 99.99% .sup.17anti-sedimentation agent of silica
type (Degussa)
iii) Results of the Saline Mist Tests: [0114] Bath according to the
invention: anticorrosion coating composition according to the
invention: the organic and aqueous phases obtained (steps ii) and
i), respectively) are mixed. [0115] Reference bath: reference
composition:
[0116] The aqueous phase of the reference composition contains:
TABLE-US-00012 Water 463 parts by weight Sodium silicate 20 N 32
8.8 parts by weight Boric acid 8.2 parts by weight Molybdenum oxide
9 parts by weight Silane A 187 31 parts by weight
[0117] The organic phase of the reference composition has the same
composition as the organic phase of the bath according to the
invention (step ii)).
[0118] The saline mist tests are carried out after an ageing of the
baths, according to the invention and reference, of the order of 48
hours. The results obtained are given in table 11 below:
TABLE-US-00013 TABLE 11 Results on steel Results on screws support
(5.sup.d/4.8.sup.e) Sacrificial Such as V + CM.sup.a 2 .times.
G.sup.b protection.sup.c 2 .times. G.sup.b Reference bath 672/672
456/840 168/336 624 168 Bath according to >1150 840/912 336/576
1150 744 the invention .sup.aV + CM: saline mist results after the
screws had been subjected to the mechanical shocks of vibrations
and falls. .sup.b2 .times. G: saline mist results after the screws
or the plates had been subjected twice to chipping, that is to say
a spattering of impacts. .sup.cSacrificial protection: number of
hours of exposure to the saline mist, without red rust after
incision of the coating to the metal. .sup.dnotation 5: results
corresponding to less than 1% of red rust on surface.
.sup.enotation 4.8: results corresponding to less than 5% of red
rust on surface. Table 11 makes it appear clear that the
introduction of chelated organic titanate, compatible in aqueous
phase, co-hydrolysed with the silane in the coating compositions
increases the good behaviour to saline mist of the samples treated
by these compositions.
* * * * *