U.S. patent application number 11/106032 was filed with the patent office on 2006-10-19 for process for the coating of metallic components with an aqueous organic composition.
Invention is credited to Heribert Domes, Noel Smith.
Application Number | 20060233955 11/106032 |
Document ID | / |
Family ID | 36607296 |
Filed Date | 2006-10-19 |
United States Patent
Application |
20060233955 |
Kind Code |
A1 |
Smith; Noel ; et
al. |
October 19, 2006 |
Process for the coating of metallic components with an aqueous
organic composition
Abstract
The invention relates to a process for the coating of surfaces
of a metallic component to be formed by at least one forming
operation like cold-forming, cold-forging, roll-stamping,
roll-forming, deep-drawing or wire-drawing by contacting the
surfaces of the metallic component before the forming operation
with an aqueous composition that contains predominantly organic
polymeric material whereby the aqueous composition contains at
least one compound each of: A) organic film-forming polymeric
material(s) selected from the group consisting of ionomeric
copolymers, copolymers chemically related to ionomeric copolymers
showing nearly or totally the properties of ionomeric copolymers
and their corresponding monomers, comonomers, oligomers,
cooligomers, polymers, blockcopolymers as well as their esters,
salts and derivates, which all together are constituents of at
least 80% by weight of the total organic polymeric material and
whereby the total organic polymeric material has an average acid
number in the range from 20 to 300, A') optionally at least one
further organic film-forming polymer or their corresponding
monomer(s), oligomer(s), copolymer(s), blockcopolymer(s), their
derivates or any combination of them that do not belong to A)
participating in the rest of the total organic polymeric material
to 100% by weight, B) optionally neutralizing agent(s), C) low
temperature corrosion inhibiting cross-linking agent(s) and D)
water, whereby the pH of the aqueous composition is at the
beginning of the coating process in the range from 6 to 10.5.
Inventors: |
Smith; Noel; (Hackettstown,
NJ) ; Domes; Heribert; (Weilmunster, DE) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI, LLP
666 FIFTH AVE
NEW YORK
NY
10103-3198
US
|
Family ID: |
36607296 |
Appl. No.: |
11/106032 |
Filed: |
April 14, 2005 |
Current U.S.
Class: |
427/299 ;
427/402; 427/430.1; 427/487 |
Current CPC
Class: |
C09D 5/002 20130101;
Y10T 428/1355 20150115; C09D 5/4411 20130101; Y10T 428/31699
20150401; Y10T 428/24628 20150115 |
Class at
Publication: |
427/299 ;
427/430.1; 427/487; 427/402 |
International
Class: |
B05D 3/00 20060101
B05D003/00; B05D 7/00 20060101 B05D007/00; C08F 2/46 20060101
C08F002/46; B05D 1/36 20060101 B05D001/36; B05D 1/18 20060101
B05D001/18 |
Claims
1. A process for the coating of surfaces of a metallic component to
be formed by at least one forming operation like cold-forming,
cold-forging, roll-stamping, roll-forming, deep-drawing or
wire-drawing by contacting the surfaces of the metallic component
before the forming operation with an aqueous composition that
contains predominantly organic polymeric material whereby the
aqueous composition contains at least one compound each of: A)
organic film-forming polymeric material(s) selected from the group
consisting of ionomeric copolymers, copolymers chemically related
to ionomeric copolymers showing nearly or totally the properties of
ionomeric copolymers and their corresponding monomers, comonomers,
oligomers, cooligomers, polymers, blockcopolymers as well as their
esters, salts and derivates, which all together are constituents of
at least 70% by weight of the total organic polymeric material and
whereby the total organic polymeric material has an average acid
number in the range from 20 to 300, A') optionally at least one
further organic film-forming polymer or their corresponding
monomer(s), oligomer(s), copolymer(s), blockcopolymer(s), their
derivates or any combination of them that do not belong to A)
participating in the rest of the total organic polymeric material
to 100% by weight, B) optionally neutralizing agent(s), C) low
temperature corrosion inhibiting cross-linking agent(s) and D)
water, whereby the pH of the aqueous composition is at the
beginning of the coating process in the range from 6 to 10.5.
2. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the ionomeric or nearly ionomeric
copolymeric organic film-forming polymer(s) A) are selected from
the group consisting of materials containing predominantly
ethylene/propylene acrylic acid copolymers, ethylene/propylene
methacrylic acid copolymers, ethylene/propylene maleic anhydride
copolymers or ethylene/propylene naphthalic anhydride copolymers,
their corresponding monomers, comonomers, oligomers, cooligomers,
polymers, blockcopolymers as well as their corresponding esters,
salts and derivates and any combination of these.
3. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the aqueous composition or the
organic ionomeric or nearly ionomeric polymeric material or any
combination thereof for the aqueous composition is prepared by
heating up an aqueous polymeric base composition containing at
least one of the organic polymeric materials having an acid number
in the range from 50 to 250 and at least one neutralizing agent to
temperatures in the range from 50 to 150.degree. C. for a time of
at least half a minute whereby at least one organic polymeric
material is neutralized, then by cooling and moving the composition
which has then a pH in the range from 6 to 10.5.
4. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the at least one neutralizing agent
B) for the organic polymeric material is selected from the group
consisting of ammonia and of any other volatile alkaline
neutralizer.
5. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the at least one low temperature
corrosion inhibiting cross-linking agents C) is selected from the
group consisting of compounds of lithium, sodium, potassium,
rubidium, cesium, calcium, magnesium, strontium, barium, yttrium,
titanium, hafnium, zirconium, manganese, iron, cobalt, nickel,
copper, zinc, niobium, molybdenum, boron, silicon like a
silane/silanol/siloxane/polysiloxane, phosphorus and at least one
lanthanide containing compounds.
6. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the low temperature corrosion
inhibiting cross-linking agents C) complex a chemical group of
organic film-forming polymeric material(s) and cause the
insolubility of the organic polymeric material(s) after drying.
7. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the low temperature corrosion
inhibiting cross-linking agents C) contain particles,
nanoparticles, gels, sols or any combination of these of inorganic
materials like oxides, hydroxides, carbonates, water-insoluble
sulfates, silicates or any combination thereof.
8. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the low temperature corrosion
inhibiting cross-linking agents C) are blocked.
9. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby there is further added to the aqueous
composition at least one constituent selected from the group
consisting of: a) acidic catalyst(s), b) rheology controlling
agent(s), c) wetting agent(s), d) adhesion promoting agent(s), e)
film-forming agent(s), f) defoaming agent(s), g) UV absorber(s),
light stabilizer(s) or both, h) further agent(s) like
photoinitiators, like antioxidants, like dyes, like coloring
pigments as well as like other types of cross-linkers and j)
organic solvent(s).
10. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the aqueous composition contains at
least one chromium compound selected from the group consisting of
chromates and dichromates of ammonium, lithium, sodium and
potassium.
11. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the coating generated with the
aqueous composition has the function of a pretreatment primer.
12. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the aqueous composition as well as
the composition of the drying film or of the dried film are such
that the cross-linking of the organic polymeric material may be
performed at a temperature in the range from 5 to 85.degree. C.
13. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the coating is dried at a temperature
below 65.degree. C.
14. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the aqueous composition contains at
least one other type of cross-linker and whereby the generated
coating is further cross-linked starting at low or high
temperature.
15. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the coating contains at least one
other type of cross-linker and whereby the generated coating is
further cross-linked starting with a temperhardening or with
another kind of heating.
16. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the aqueous composition contains at
least one photoinitiator and actinically cross-linkable monomers
and whereby the generated coating is further cross-linked starting
by actinic irradiation.
17. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the coating generated with the
aqueous composition is afterwards coated with at least one layer
each of a primer, a powder paint, a base coat, a clear coat, an
adhesive or any combination of these.
18. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby there is further applied a coating
from a composition containing at least one forming agent like any
oil or wax or both on the coating prepared with the aqueous
composition as claimed in claim 1 whereby the such coated metallic
component may be used for a heavy forming operation like
deep-drawing.
19. The process for the coating of surfaces of a metallic component
as claimed in claim 1 whereby the coating generated with the
aqueous composition is joined by the aid of at least one adhesive
with any paper, any foil, any sheet or any other part.
20. A coating generated with a process as claimed in claim 1.
21. A coated metallic component coated by a process as claimed in
claim 1.
22. A method of use of a metallic component coated by a process as
claimed in claim 1 for corrugated iron, gutters, profiles, tubings,
automotive stampings, housings, electronic equipment, guard rails,
inside or outside architectural use, aerospace industry, automotive
industry, apparatuses, appliance industry, construction, roofing,
siding, transport, ventilating, cylinders, fasteners, shafts,
containers or tanks.
Description
[0001] The invention relates to a process for the coating of a
metallic component to be formed by at least one forming operation
like cold-forming, cold-forging, roll-stamping, wire-drawing,
deep-drawing or roll-forming by contacting the metallic component
before the forming operation with an aqueous composition that
contains predominantly organic polymeric material as well as to a
method of the use of such coated components.
BACKGROUND OF THE INVENTION
[0002] Such aqueous compositions may be used to coat metallic
components like coils, sheets, plates, foils, plastic laminated
metal foils and other laminated components, parts of any shape or
wires or any combination of these to generate organic coatings with
a high flexibility and high resistance against corrosion. Such
compositions may be used for the production e.g. of corrugated
iron, gutters, profiles, tubings, automotive stampings, housings,
electronic equipment or guard rails. Such components may further be
used for inside or outside architectural use, aerospace industry,
automotive industry, apparatuses, appliance industry, construction,
roofing, siding, transport, ventilating, cylinders, fasteners,
shafts, containers or tanks. Such compositions may be even used as
so-called dry-lubes for the cold-forming of components like
cylinders, fasteners, shafts, containers or tanks.
[0003] Many of the existing aqueous compositions used for such
coatings and for the thereof resulting products are formulated for
demanding coating conditions and specific coating properties.
Because of specifically selected raw materials, such compositions
are often expensive. Therefore, there was the need to look for
alternative raw material sources and alternative compositions that
may lead to coated metallic components that may be well formed by
any forming operation and that render a sufficient corrosion
resistance as well as paint adhesion if the coated components would
be painted afterwards.
SUMMARY OF THE INVENTION
[0004] It was an object of the present invention to form thin
organic corrosion protecting coatings at temperatures below
80.degree. C. PMT (peak-metal-temperature). It was a further object
to propose compositions and coatings to be used with chromium
compounds or in alternative without chromium compounds. It was
further an object of the present invention to lower the costs of
the raw materials selected to be used for the aqueous composition
as well as the costs of the process.
[0005] It has been found that if a significant content of a wax
dispersion was added to the aqueous organic composition, there
typically occurred trouble as this addition affected the stability
of the aqueous composition as well as the properties of the
coatings generated therewith like the corrosion resistance. Such
aqueous compositions containing a content of a wax gelled or were
often jelly or become soon jelly. It has further on been found that
there is no need of adding any wax as the forming properties of the
coatings of the invention are as sufficient that there is no need
to add any wax to the aqueous composition as the coatings generated
are sufficient flexible and lubricious not to be affected during
the forming of the metallic component and allow a forming operation
without an increase of forces and of wear.
[0006] The object is achieved by a process for the coating of
surfaces of a metallic component to be formed by at least one
forming operation like cold-forming, cold-forging, roll-stamping,
roll-forming, deep-drawing or wire-drawing by contacting the
surfaces of the metallic component before the forming operation
with an aqueous composition that contains predominantly organic
polymeric material whereby the aqueous composition contains at
least one compound each of:
[0007] A) organic film-forming polymeric material(s) selected from
the group consisting of ionomeric copolymers, copolymers chemically
related to ionomeric copolymers showing nearly or totally the
properties of ionomeric copolymers and their corresponding
monomers, comonomers, oligomers, cooligomers, polymers,
blockcopolymers as well as their esters, salts and derivates, which
all together are constituents of at least 70% by weight of the
total organic polymeric material and whereby the total organic
polymeric material has an average acid number in the range from 20
to 300, A') optionally at least one further organic film-forming
polymer or their corresponding monomer(s), oligomer(s),
copolymer(s), blockcopolymer(s), their derivates or any combination
of them that do not belong to A) participating in the rest of the
total organic polymeric material to 100% by weight,
[0008] B) optionally neutralizing agent(s),
[0009] C) low temperature corrosion inhibiting cross-linking
agent(s) and
[0010] D) water,
[0011] whereby the pH of the aqueous composition is at the
beginning of the coating process in the range from 6 to 10.5, often
in the range from 7 to 10.
[0012] Preferably, the organic film-forming polymeric materials A)
and optionally at least one further organic film-forming polymer
A') have a certain amount or high amount of carboxyl groups. A
certain amount of carboxyl groups in the aqueous composition as
used for the coating is helpful for the reaction with the metallic
surface. Optionally, the percentage of copolymers in the total
organic polymeric material is in the range from 75 to 100 percent
by weight.
[0013] According to the invention, there may be prepared a
dispersion containing at least one organic film-forming polymeric
material A) as starting composition for the aqueous composition or
there may be taken at least one dispersion containing at least one
organic film-forming polymeric material A) as one of the raw
materials added to the aqueous composition of the invention.
[0014] There must not be present any neutralizing agent B) in the
aqueous composition according to the invention. As neutralizing
agents, ammonium hydroxide, amine-based compounds like a trialkyl
amine as well as potassium hydroxide if only used in smaller amount
are preferred. The ammonium hydroxide and some of the amine-based
compounds will more or less evaporate. The at least one
neutralizing agent shall help to generate an aqueous dispersion of
the copolymeric material(s) by solubilization. If sodium or higher
amounts of potassium compounds would be added, this may cause in
many cases a water-sensitive organic coating which is not
preferred. The term "dispersion" shall include solutions. In many
cases, the at least one neutralizing agent helps to neutralize the
often more or less acidic copolymeric materials that will be
dissolved or dispersed or both in water or in the aqueous
composition if the organic film-forming polymeric materials A) and
optionally at least one further organic film-forming polymer A')
are heated in water in the presence of at least one neutralizing
agent. Such dispersion will have in many cases a low viscosity if
the carboxyl groups of the copolymeric material(s) are only
partially neutralized, preferably neutralized to 20 to 85%, more
preferred to 30 to 80%, most preferred to 40 to 70%, especially to
50 to 60%. Such only partially neutralized dispersions are often of
low viscosity whereas the viscosity may increase with the degree of
neutralization, sometimes even up to a paste-like material. By the
heating in the presence of water and of at least one neutralizing
agent, an ion containing copolymeric material is produced.
Typically, the ions contained in the copolymeric material are bound
and ionize carboxyl groups. Therefore, the bound ions are no longer
able to ionize compounds present in water. If the aqueous
dispersion gets in contact with a metallic surface, the ions coming
out of the metallic materials of the surface may be bound in the
ionomeric polymeric material, too. By such heating and
neutralizing, a dispersion of low viscosity may be prepared. There
may be a further content of neutralizing agent(s) in the dispersion
as this reaction and dispersing takes primarily or only place
during the heating. If such a dispersion is added to the aqueous
composition, then there is no need to add any neutralizing
agent.
[0015] Preferably, at least one neutralizing agent is evaporating
from the wet film of the aqueous composition on the metallic
surface or is chemically reacted in any way generating a pH in the
range from 4 to 10 in the drying film or both. Preferably, at least
a part of the ionomeric copolymeric materials or of the copolymeric
materials related to ionomeric copolymeric materials or of any
combination of these have carboxyl groups which may be used in such
chemical reaction. This reaction may help to solubilize and dispers
the copolymeric material(s). This chemical reaction may occur with
the help of at least one alkaline compound, of at least one acidic
catalyst, sometimes even with the help of another constituent or
with the help of any combination of these. Further on, there may be
added several constituents like agents for specific tasks as well
as at least one organic solvent.
[0016] Preferably, a dry film (the "coating") is generated which
enables the film-formation and the solidification by drying at a
temperature significantly below 100.degree. C. or at a temperature
slightly above room temperature or even at room temperature or at
any combination of these temperature ranges.
[0017] The aqueous compositions according to the invention are
preferably free of any wax and of any oil. A wax according to the
invention shall mean a compound that has a defined melting point,
that has a relatively low viscosity if it is molten and that is
able to occur in a crystalline form. Typically, a wax does not show
a significant or even any content of carboxyl groups, is hydrophobe
and is to a high extent chemically inert.
[0018] Preferably, there is no addition or no intentional addition
or no essential addition of any surfactant, of any heavy metal like
cadmium, cobalt, copper, molybdenum, nickel, tin or tungsten or any
combination of these, especially to avoid poisonous substances like
heavy metals and to avoid environmentally unfriendly compounds like
phosphate based surfactants or chlorinated compounds as far as
possible or to avoid disturbing compounds like surfactants.
Nevertheless, there exists the old problem to be forced to use
chromium compounds in many applications because of their excellent
corrosion protection behavior. In some cases it is more preferred
that the amount of such compounds is reduced to a minimum or near
to such minimum if it would be necessary or advisable to add any
such component(s) at all. The addition of surfactants seems in many
cases not to be necessary as there is a good wetting behavior of
the organic polymeric material especially if this has a higher acid
number.
[0019] According to another feature of the invention, there is a
coating generated with the process according to the invention.
[0020] According to a further feature of the invention, there is a
coated metallic component that is coated by a process according to
the invention.
[0021] According to a further feature of the invention, there is a
method of use of the coated metallic component according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The metallic component coated may be of any metallic
material like steel, cold rolled steel, hot rolled steel, stainless
steel, zinc, a zinc alloy, aluminum, aluminum alloy, magnesium
alloy, titanium, titanium alloy, copper, any copper alloy like
brass and bronze, tin and any tin alloy like a tin lead alloy. The
metallic component coated may be of any metallic material and may
be of any shape.
[0023] The metallic component may be precoated with a metallic
coating e.g. of zinc, a zinc alloy, a nickel alloy, a cobalt alloy,
a silicon alloy, a tin alloy, copper, a copper alloy, an aluminum
alloy, an aluminum and zinc containing alloy like Galfan.RTM., like
Galvaneal.RTM. or like Galvalume.RTM..
[0024] The surface of the metallic component may be anodized,
especially if it contains aluminum, magnesium, titanium or any
combination of these.
[0025] The surface of the metallic component may be precoated,
especially with at least one layer e.g. of a pretreatment
composition like any phosphate coating, any chromate coating, any
coating containing titanium, zirconium,
silane/silanol/siloxane/polysiloxane or any combination of these or
any other layer rendering the metallic surface corrosion resistance
or paint adhesion or both. This at least one layer may be a very
thin layer like a monolayer of any substance like a surfactant, but
it has to be taken care that a contamination with any surfactant
does not affect the coating with the aqueous coating composition
according to the invention.
[0026] The aqueous composition may preferably consist essentially
of the constituents A) and C) as well as optionally of at least one
of the constituents selected from the group consisting of
constituents A'), B) and a) to j). Nevertheless, there may then be
further a small amount of at least one further compound or type of
ion or both here to be seen as "non-essential" like impurities e.g.
coming from raw materials, compounds or ions or both that were
introduced into the aqueous composition e.g. by pickling or by any
alkaline effect e.g. with the tubes and bath container walls, not
intentionally added compounds that have been dragged in e.g. from
another bath or any combination of these.
[0027] The term "comonomers, monomers, oligomers, cooligomers,
polymers, copolymers, blockcopolymers as well as their esters,
salts and derivates" shall include all kinds of preoligomers,
precooligomers, prepolymers, precopolymers and preblockcopolymers.
The term "polymeric" or "copolymeric" or both terms together shall
indicate in a broad sense that there may be present monomers,
comonomers, oligomers, cooligomers, polymers, copolymers,
blockcopolymers as well as their esters, salts and derivates. Such
terms comprise terpolymers and graft polymers, too. The term
"cross-linking" shall include the densification of the coating to
form a homogeneous film by film-forming, in some of the embodiments
with the aid of a film-forming agent e).
[0028] Ionomeric polymeric materials are typically organic
polymeric materials with ionic sites that have been reacted at
least partially with counterions or that will be reacted at least
partially with during the crosslinking e.g. of the wet film and
perhaps even later in the dry film ("the coating"). The ionomeric
polymeric materials may contain as raw materials, as cross-linked
organic materials or both nonionic repeat units and often a mostly
small amount of ion containing repeat units. Often, the ionic
groups will mostly be less than 30% or even less than 15% by weight
of the ionomeric polymeric material(s). The ionomeric polymeric
materials differ clearly from waxes.
[0029] The ionomeric organic film-forming copolymer(s) as
constituent A) to be added to the aqueous composition are
preferably selected from the group of materials containing
predominantly ethylene/propylene acrylic acid copolymers,
ethylene/propylene methacrylic acid copolymers, ethylene/propylene
maleic anhydride copolymers or ethylene/propylene naphthalic
anhydride copolymers or any combination of these. They may even
contain as constituent A) to be added to the aqueous composition
preferably polymeric materials on the base of styrene, butadiene,
urethane, fumaric acid, sulfonic acid or any combination of these
or of any of these in any combination with the polymeric materials
just mentioned before. They may contain a minor content or traces
each of at least one compound selected from the group consisting of
their corresponding monomers, comonomers, oligomers, cooligomers,
polymers, blockcopolymers as well as their corresponding esters,
salts and derivates. In the following, the term
"ethylene/propylene" shall mean that either ethylene or propylene
or both may be present.
[0030] The ionomeric or the nearly ionomeric organic film-forming
copolymeric material(s) or both as constituent(s) A) to be added to
or contained in the aqueous composition are more preferred selected
from the group consisting of ethylene/propylene acrylic acid
copolymers, ethylene/propylene methacrylic acid copolymers,
ethylene/propylene maleic anhydride copolymers, ethylene/propylene
naphthalic anhydride copolymers, their corresponding monomers,
comonomers, oligomers, cooligomers, polymers, blockcopolymers as
well as their corresponding esters, salts and derivates as well as
any combination of these. These organic film-forming copolymer(s)
preferably have at least partially any groups e.g. like acrylate,
butyl, ethyl, isobutyl, methyl, propyl and vinyl. Especially the
copolymers, esters, salts and some of the derivates may in some
embodiments contain a content of ammonium, sodium, potassium,
calcium, magnesium, aluminum, iron, manganese, titanium, zinc,
zirconium or any combination of these. But in some cases, there may
be used at least one other cation alone or together with at least
one of the cations just mentioned before. The cations may
preferably be added during the neutralization of the polymeric
material.
[0031] In this status, the neutralized ionomeric or nearly
ionomeric copolymeric materials are typically thermoplastics that
have ionic cross-links and that may be called reversible
cross-linkers, but they are not yet cross-linked polymeric
materials. On heating, the ionic groups may loose their attractions
and some chains may freely move around. Then, these polymeric
materials will often show the properties of elastomers and the
processability of thermoplastics.
[0032] Many ionomeric or nearly ionomeric copolymeric materials
have a content of acrylic acid or methacrylic acid or both in a
total range from 5 to 30% by weight, often in a total range from 10
to 28% by weight. Many ionomeric or nearly ionomeric copolymeric
materials have a content of ethylene/propylene acrylic acid,
ethylene/propylene methacrylic acid or both in a total range from
60 to 95% by weight, often in a total range from 72 to 90% by
weight. In many cases, there will be a content in the range from
0.1 to 10% by weight selected from the group consisting of
monomers, comonomers, oligomers, cooligomers, polymers,
blockcopolymers as well as their corresponding esters, salts and
derivates or in the range from 0.1 to 10% by weight of further
constituents as often added to such dispersions--not calculating
water and organic solvent--or any combination of these. Often, such
copolymeric materials show a low crystallinity and are bondable,
paintable, clear, water vapor permeable and tough. In many
embodiments, the content of ionomeric comonomers and monomers
together as parts of the constituent A) is less than 25% by weight,
often less than 15% or even less than 5% by weight, typically less
than 1%. Often, the film forming temperature of the aqueous
composition is at least 1.degree. C., preferably of at least
20.degree. C., in several cases of at least 40.degree. C.
[0033] The blockcopolymers and copolymers of ionomeric or nearly
ionomeric copolymeric materials may further contain e.g. butyl
groups, acrylate, neopentyl, ethylene oxide, propylene oxide, vinyl
groups, dimethyl, acrylamide, lactide, naphthalene, styrene as well
as other specific organic segments and groups. Such blockcopolymers
may be based e.g. on acrylic acid--acrylic acid, acrylic
acid--methacrylic acid and methacrylic acid--methacrylic acid and
optionally on other organic groups and substances.
[0034] Preferably, the ionomeric polymeric materials to be used
with the process of the invention have a melting point in the range
from 30 to 300.degree. C. measured according to ASTM D3418, more
preferred in the range from 50 to 120.degree. C., most preferred in
the range from 65 to 90.degree. C.
[0035] Preferably, the ionomeric or nearly ionomeric copolymeric
materials to be used with the process of the invention have a glass
transition temperature T.sub.g in the range from -30 to 60.degree.
C. measured according to ASTM D3418, more preferred in the range
from -15 to 30.degree. C., most preferred in the range from -10 to
20.degree. C.
[0036] Preferably, the ionomeric or nearly ionomeric copolymeric
materials to be used with the process of the invention have a
molecular weight in the range from 2000 to 100000, more preferred
in the range from 4000 to 50000, most preferred in the range from
5500 to 13000.
[0037] By using such ionomeric or nearly ionomeric organic
compounds as constituent A), there is a wax-like behavior of the
coatings achieved.
[0038] Preferably, the percentage of copolymers in the organic
film-forming polymeric material(s) A) is in the range from 85 to
100 percent by weight, more preferred in the range from 90 to 99.5
percent by weight, most preferred in the range from 92 to 99
percent by weight.
[0039] Preferably the percentage of copolymers in the total organic
polymeric material is in many embodiments in the range from 60 to
100 percent by weight, more preferred in the range from 80 to 100
percent by weight, most preferred in the range from 90 to 100
percent by weight, especially in the range from 92 to 99 percent by
weight, e.g. at about 94, 96 or 98 percent by weight.
[0040] In many embodiments according to the invention, there is
added at least one dispersion to the aqueous composition going to
be composed containing at least a portion or the whole portion of
the organic film-forming polymeric material A) to be added. Such
dispersion may contain besides of the at least one copolymer minor
contents or traces of at least one compound selected from the group
consisting of monomers, comonomers, oligomers, cooligomers,
polymers, blockcopolymers as well as their esters, salts and
derivates corresponding to the ionomeric copolymers or to the
copolymers chemically related to ionomeric copolymers ("the nearly
ionomeric copolymeric materials") showing nearly or totally the
properties of ionomeric copolymers or to both. Such dispersions may
contain as solid materials predominantly at least one compound
selected from the group consisting of ionomeric copolymers and
copolymers chemically related to ionomeric copolymers showing
nearly or totally the properties of ionomeric copolymers,
preferably at least 90% by weight or at least 95% by weight of the
solid materials of such dispersions. Such dispersions may contain a
content of at least one type of cations selected from the group
consisting of ammonium, sodium, potassium, calcium, magnesium,
aluminum, iron, manganese, zinc and any combination of these. The
further constituents of such dispersions are to be seen as
constituents of the organic copolymeric material(s) A).
[0041] Such dispersions may in many cases be anionically or
non-ionically stabilized or anionically and non-ionically
stabilized or any mixture of these. Such acidic dispersions which
have a significant amount of carboxyl groups may then be
neutralized to a pH of at least 6 or of at least 7. Such
dispersions may in many cases show a small content of at least one
alkaline compound like sodium hydroxide or ammonium hydroxide
respectively their corresponding ions or of at least one acid
respectively their corresponding ions or any combination of these.
Such dispersions may in many cases show a pH in the range from 6 to
10.5, more preferred in the range from 7 to 10, most preferred in
the range from 7.5 to 9.5. If the pH would be too high, the polymer
might be chemically attacked or destroyed.
[0042] According to one of the definitions existing for ionomeric
organic copolymeric materials, such materials have a content
especially of sodium, potassium, calcium, magnesium, zinc or any
combination of these, but not predominantly of ammonium. According
to another definition, even ammonium ions may contribute to the
generation of an ionomeric copolymeric material. If there are
predominantly or only cations of ammonium added, these copolymers
should not be called ionomeric copolymers, but may be one type of
nearly ionomeric copolymeric materials. Nevertheless, if
copolymeric materials containing predominantly or only cations of
ammonium are to be added to the aqueous composition according to
the invention, the copolymeric materials in the aqueous composition
and in the resulting coating will often behave or nearly behave
like typical ionomeric copolymeric materials. The addition of at
least one dispersion containing at least one copolymer to the
aqueous composition is preferred as such addition may help to
homogeneously dispers the copolymeric material in the aqueous
composition and in the coating.
[0043] The total organic polymeric material or the copolymeric
material(s) A) or both have preferably an average acid number in
the range from 50 to 250, more preferred in the range from 100 to
225 and most preferred in the range from 140 to 200, especially at
about 130, at about 150, at about 160, at about 170, at about 180
at about 190 or at about 210 or in any ranges in between any of
these data. The ionomeric or nearly ionomeric copolymeric material
often has a relatively high acid number compared with most of the
known organic materials of dispersions based on e.g. acrylic
polymeric materials. It has been found that a significantly better
cross-linking degree may be reached with the copolymeric materials
of this invention than with most other organic polymeric materials
if no high temperature cross-linking agent and no photoinitiator is
used, probably often a cross-linking degree in the range from 50 to
99% or more often of 60 to 95%--as far as up to now known--whereas
the cross-linking degree of other organic polymeric materials is
often in the range from 20 to 60% if there is a film-forming
process without any high temperature cross-linkers used. There may
be even a slow further cross-linking of longer time with any low
temperature cross-linker.
[0044] If there would be any addition of at least one low
temperature or high temperature cross-linker like compounds based
on isocyanate, isocyanurate or melamine or any blocked
cross-linkers or any combination of such cross-linkers, there may
be a significantly higher chemical resistance and mechanical
resistance of the coating whereby the flexibility may be lowered
and often even the corrosion protection is not further improved.
Especially, if there is a content of an organic polymeric material
A') having a certain amount of e.g. hydroxyl groups like any
acrylics may be used together with such cross-linkers to enhance
the properties of the polymeric coating. Such cross-linkers may be
selected according to the temperature from which the cross-linking
shall be started. Such agent may be effective starting at a
temperature in a range of about 15 to about 240.degree. C. If there
is a coating that has been generated with an aqueous composition
showing a content of at least one photoinitiator or at least one
other type of cross-linker or of both, there is a possibility to
have a coating that is formed with any forming operation being only
or predominantly cross-linked with the low temperature corrosion
inhibiting cross-linking agent(s) C). The aqueous composition
containing at least one other type of cross-linker may preferably
be further cross-linked starting at low temperature or at high
temperature or both and being then further cross-linked, optionally
even over short or long term further on after the heating. During
the forming operation or afterwards or both, at its forming
temperature, the forming coating or the formed coating may
preferably be heated up or may be heated up to at least the
starting temperature of the cross-linking of the chemical
cross-linker(s), e.g. by temperhardening or by any other heating
operation. Preferably, the coating containing at least one other
type of cross-linker is further cross-linked starting with a
temperhardening or with another kind of heating. Alternatively,
there may be at any time an actinic irradiation that causes the
start of the actinic cross-linking e.g. by UV irradiation.
Preferably, the aqueous composition containing at least one
photoinitiator and actinically crosslinkable monomers may be
further cross-linked starting by actinic irradiation. There may be
even a combination of a chemical and an actinic cross-linking,
especially after the forming operation. Further on, there is a
possibility to use any compound e.g. based on isocyanate as a low
temperature cross-linker but typically this is no corrosion
inhibiting cross-linking agent which is used, too, as a
cross-linking agent. There may be even an actinic cross-linking if
there is added at least one photoinitiator together with an amount
of monomers to be cross-linked in this way to the aqueous
composition. By using not only the low temperature corrosion
inhibiting cross-linking agent(s) C) for the cross-linking, but
even at least one photoinitiator or at least one other type of
cross-linker or both, there may be a significant higher
cross-linking degree and a significant improvement of the coating
properties.
[0045] The percentage of copolymers in the total organic polymeric
material is preferably in the range from 2 to 35 percent by weight,
more preferred in the range from 5 to 30 percent by weight and most
preferred in the range from 12 to 25 percent by weight, especially
at about 10, at about 12, at about 14, at about 16, at about 18, at
about 20, at about 22, at about 24, at about 26 or at about 28
percent by weight or in any ranges in between any of these
data.
[0046] The relation of the total organic polymeric material to the
total solids' content may be varied in broad ranges. Preferably,
this relation is in the range from 75 to 99%, more preferred in the
range from 85 to 98%, in the range from 90 to 97%.
[0047] The content of total organic polymeric material A) plus A')
in the aqueous composition may preferably be varied in the range
from 40 to 440 g/L calculated as the active compounds, more
preferred in the range from 70 to 400 g/L, much more preferred in
the range from 100 to 370 g/L, most preferred in the range from 95
to 340 g/L especially in the range from 110 to 310 g/L, especially
of about 100 g/L, of about 120 g/L, of about 130 g/L, of about 140
g/L, of about 150 g/L, of about 160 g/L, of about 170 g/L, of about
180 g/L, of about 190 g/L, of about 200 g/L, of about 210 g/L, of
about 220 g/L, of about 230 g/L, of about 240 g/L, of about 250
g/L, of about 260 g/L, of about 270 g/L, of about 280 g/L, of about
290 g/L or of about 300 g/L or in any ranges in between any of
these data.
[0048] The content of the film-forming organic ionomeric or nearly
ionomeric copolymer(s) A) in the aqueous composition may preferably
be varied in the range from 35 to 440 g/L calculated as the active
compounds, more preferred in the range from 50 to 390 g/L, much
more preferred in the range from 70 to 350 g/L, most preferred in
the range from 80 to 310 g/L especially in the range from 90 to 270
g/L, especially of about 100 g/L, of about 120 g/L, of about 130
g/L, of about 140 g/L, of about 150 g/L, of about 160 g/L, of about
170 g/L, of about 180 g/L, of about 190 g/L, of about 200 g/L, of
about 210 g/L, of about 220 g/L, of about 230 g/L, of about 240
g/L, of about 250 g/L, of about 260 g/L, of about 270 g/L, of about
280 g/L, of about 290 g/L or of about 300 g/L or in any ranges in
between any of these data.
[0049] The content of the at least one further film-forming organic
polymer/copolymer/blockcopolymer A') or their corresponding
monomer(s)/oligomer(s) or any combination of these participating in
the rest of the total organic polymeric material to 100% by weight
in the aqueous composition may be zero or may preferably be varied
in the range from 1 to 90 g/L calculated as the active compounds,
more preferred in the range from 5 to 80 g/L, much more preferred
in the range from 15 to 70 g/L, most preferred in the range from 30
to 60 g/L, especially of about 10 g/L, of about 20 g/L, of about 30
g/L, of about 40 g/L, of about 50 g/L, of about 60 g/L, of about 70
g/L or of about 80 g/L or in any ranges in between any of these
data.
[0050] The content of the at least one further film-forming organic
polymer/copolymer/blockcopolymer A') or their corresponding
monomer(s)/oligomer(s) or any combination of these participating in
the rest of the total organic polymeric material to 100% by weight
in the aqueous composition may be zero or may preferably be varied
in the range from 0.01 to 30% by weight calculated as the active
compounds, more preferred in the range from 0.1 to 28% by weight,
much more preferred in the range from 1 to 26% by weight, most
preferred in the range from 2 to 24% by weight, especially of about
3% by weight, of about 5% by weight, of about 7% by weight, of
about 9% by weight, of about 11% by weight, of about 13% by weight,
of about 15% by weight, of about 17% by weight, of about 19% by
weight, of about 21% by weight or of about 23% by weight or in any
ranges in between any of these data.
[0051] The total solids' content of the aqueous composition may
preferably be varied in the range from 50 to 450 g/L, more
preferred in the range from 70 to 400 g/L, much more preferred in
the range from 90 to 350 g/L, most preferred in the range from 100
to 300 g/L, especially in the range from 150 to 270 g/L, especially
of about 100 g/L, of about 120 g/L, of about 130 g/L, of about 140
g/L, of about 150 g/L, of about 160 g/L, of about 170 g/L, of about
180 g/L, of about 190 g/L, of about 200 g/L, of about 210 g/L, of
about 220 g/L, of about 230 g/L, of about 240 g/L, of about 250
g/L, of about 260 g/L, of about 270 g/L, of about 280 g/L, of about
290 g/L or of about 300 g/L or in any ranges in between any of
these data. If there is a lower solids' content, then there may
often be a higher viscosity used to achieve the same coating
weights.
[0052] According to the process of the invention, the organic
copolymeric material(s) A) or the total organic polymeric material
or both may preferably show an average melt index measured
according to ASTM D 1238 in the range from 5 to 2000 g/10 min. The
melt index is a function of the molecular weight and the rheology
of an organic compound especially like natural resins. The melt
index of an ethylene acrylic acid may be in the range from 5 to
5000, often in the range from 15 to 1500, sometimes in the range
from 100 to 800. Often, such melt index is used for a solvent based
organic polymer system.
[0053] According to the process of the invention, the aqueous
composition or the organic ionomeric or nearly ionomeric
copolymeric material(s) for the aqueous composition or any
combination of these may preferably be prepared by heating up an
aqueous copolymeric base composition containing at least one of the
organic copolymers having an acid number preferably in the range
from 50 to 250 and at least one neutralizing agent to temperatures
preferably in the range from 50 to 150.degree. C. for a time of at
least half a minute whereby the organic polymeric material is
neutralized preferably for at least 50%, then by cooling and moving
the composition which has then a pH in the range from 6 to 10.5,
whereby optionally a part of the same constituents or a part of all
of further constituents to be added to the aqueous composition may
be added during the heating, cooling or afterwards or in any
combination of these. The acid number is defined as the consumption
of the number of carboxyl groups during the preparation.
[0054] The content of the neutralizing agent(s) B) in the aqueous
composition may preferably be varied in the range from 1 to 50 g/L
calculated as the active compounds, more preferred in the range
from 3 to 42 g/L, much more preferred in the range from 4 to 34
g/L, most preferred in the range from 5 to 30 g/L, especially in
the range from 6 to 25 g/L, especially of about 4 g/L, of about 5
g/L, of about 6 g/L, of about 7 g/L, of about 8 g/L, of about 9
g/L, of about 10 g/L, of about 11 g/L, of about 12 g/L, of about 13
g/L, of about 14 g/L, of about 15 g/L, of about 16 g/L, of about 18
g/L, of about 20 g/L or of about 22 g/L or in any ranges in between
any of these data.
[0055] Preferably, ammonia or any other volatile alkaline
neutralizer like any compound on the base of amine like
alkanolamines, trialkylamines, triethanolamine and morpholine may
be used as a neutralizing agent B). The addition of at least one
neutralizing agent B) will typically lower the pH of the aqueous
composition. The neutralizing agent(s) are especially to be used to
neutralize the organic polymeric material. It may help to control
the pH of the aqueous composition. If there is no neutralizing
agent added, then there may be often problems to generate the
dispersion of the copolymeric material(s). If there is a too high
addition of neutralizing agent(s), then this may affect the
stability of the aqueous composition by gelling or settling. Such
agent may evaporate from the wet film, this means, during the
drying in the short time between applying the aqueous composition
onto the surface of the metallic component (=beginning of the
coating process) and reaching the dry status of the coating. As
chemical reactions in the wet film, reactions of at least one
cross-linking agent with the organic copolymeric material(s) may
occur, thereby terminating the carboxyl groups into a status of the
dispersion where the dispersion is no longer water-dispersible but
water-resistant, dry and no longer water-reemulsifiable. All these
actions assist in the preparation of a water-insoluble flexible
solid dry film, which is called the coating.
[0056] The concentrated neutralizing agent B) dissolved in water
may itself preferably have a pH in the range from 7 to 14, more
preferred in the range from 7.2 to 12. If the pH of the aqueous
composition is maintained in the range from 8 to 9, then there may
often be a better stability of the aqueous composition than if the
pH would be higher, otherwise there may be the risk of early
gelling.
[0057] The low temperature corrosion inhibiting cross-linking
agents C) may preferably be selected from the group consisting of
compounds of lithium, sodium, potassium, rubidium, cesium, calcium,
magnesium, strontium, barium, yttrium, titanium, hafnium,
zirconium, manganese, iron, cobalt, nickel, copper, zinc, niobium,
molybdenum, boron, silicon like a
silane/silanol/siloxane/polysiloxane and phosphorus and at least
one lanthanide chemical element containing compounds like cerium
compounds whereby they complex a chemical group of organic
film-forming polymeric material(s) like a carboxyl group and cause
the insolubility of the organic copolymeric material(s) after
drying. More preferred, the particles, nanoparticles, gels, sols or
any combination of these are of inorganic materials like oxides,
hydroxides, carbonates, water-insoluble sulfates, silicates or any
combination thereof e.g. of magnesium, calcium, aluminum, boron,
silicon, titanium, zirconium, hafnium, iron, manganese and zinc.
Most preferred, these compounds may be based on silica or may be
oxides, hydroxides, carbonates, water-insoluble sulfates, silicates
or any combination of these of barium, calcium, titanium, zinc,
zirconium and any combination thereof.
[0058] According to the process of the invention, the low
temperature corrosion inhibiting cross-linking agent(s) C) may
preferably be blocked. The blocking may preferably be achieved e.g.
by a metal chelate and may be deblocked in an acidic medium, e.g.
in a medium of a pH e.g. of below 7. The non-reacted blocking
compounds as well as the blocked low temperature corrosion
inhibiting cross-linking agent(s) belong to the constituent C).
[0059] The content of the low temperature corrosion inhibiting
cross-linking agent(s) C) or any combination of agents to be used
for the cross-linking of the organic copolymeric material(s) in the
aqueous composition may preferably be varied in the range from 0.1
to 100 g/L calculated as the active compounds, more preferred in
the range from 3 to 90 g/L, much more preferred in the range from 5
to 75 g/L, most preferred in the range from 7 to 60 g/L, especially
in the range from 9 to 50 g/L or in the range from 10 to 40 g/L,
especially of about 8 g/L, of about 10 g/L, of about 12 g/L, of
about 15 g/L, of about 20 g/L, of about 25 g/L, of about 30 g/L, of
about 35 g/L, of about 40 g/L, of about 50 g/L, of about 55 g/L, of
about 60 g/L or of about 65 g/L or in any ranges in between any of
these data. The amount of such agents depends essentially on the
type and on the physical condition of the material and of the
surface of the metallic component and further on of the
composition, if there is a chromium addition or not.
[0060] The total content of particles, nanoparticles, gels, sols or
any combination of these of the constituent C) in the aqueous
composition may preferably be varied in the range from 1 to 100 g/L
calculated as the active compounds, more preferred in the range
from 10 to 90 g/L, much more preferred in the range from 20 to 85
g/L, most preferred in the range from 40 to 80 g/L, especially of
about 15 g/L, of about 20 g/L, of about 25 g/L, of about 30 g/L, of
about 35 g/L, of about 40 g/L, of about 45 g/L, of about 50 g/L, of
about 55 g/L, of about 60 g/L, of about 65 g/L, of about 70 g/L, of
about 75 g/L, of about 80 g/L, of about 85 g/L or of about 90 g/L
or in any ranges in between any of these data. Preferably, the
particles, nanoparticles, gels, sols or any combination of these
are added as a powder or as a dispersion.
[0061] If there is no corrosion inhibiting cross-linking agent
added, then there may occur limited performance properties such as
a low chemical resistance and a low corrosion resistance of the
coating. If there is a too high addition of the corrosion
inhibiting cross-linking agent(s), then this may affect the
stability of the aqueous composition or the film formation by
generating flaws or both.
[0062] According to the process of the invention, the aqueous
composition may preferably contain at least one chromium compound
selected from the group consisting of chromates and dichromates of
ammonium, lithium, sodium and potassium as constituent C). The
chromium ions respectively the dried chromium compounds may be
present as Cr.sup.3+ or Cr.sup.6+ or both. If chromium compounds
are added, it is preferred to add only a limited content because of
its poisonous effects. In many cases, there is no need to add more
than 50 or more than 30 g/L of the chromate or dichromate or both.
In some cases, the coating according to the invention contains a
content of chromium in the range from 0.5 to 28 mg/m.sup.2,
sometimes in the range from 5 to 25 mg/m.sup.2, often in the range
from 8 to 15 mg/m.sup.2.
[0063] The cross-linking of the organic film-forming material(s)
may preferably be performed during the drying. According to the
process of the invention, the aqueous composition as well as the
composition of the drying film or of the dried film are more
preferred such that the cross-linking of the organic film-forming
material(s) may be performed at a temperature in the range from 5
to 80.degree. C., preferably in the range from 10 to 50.degree. C.
This low cross-linking temperature is often possible as
cross-linking agents are preferred that work in such temperature
range, especially in a temperature range of up to 60.degree. C., of
up to 50.degree. C., of up to 40.degree. C. or even up to
30.degree. C., especially at room temperature. With the process
according to the invention, the aqueous composition may be formed
e.g. at a temperature of e.g. 65.degree. C. or below e.g.
65.degree. C. without the need of any cosolvent to reduce the
temperature of film-forming for the organic copolymeric
material(s). Nevertheless, the aqueous compositions containing such
low temperature cross-linking agents will in many cases even work
at significantly higher temperatures and may optionally be used at
a high temperature much above e.g. 80.degree. C. The cross-linking
may preferably be performed with a blocked cross-linking agent that
may become active e.g. after the evaporation of at least one
alkaline compound like ammonia or after a reaction that renders the
aqueous composition less alkaline or even acidic, whereby the pH is
reduced and the cross-linking agent is deblocked. Then--in such low
temperature range of e.g. up to 50.degree. C.--the cross-linking
agent may chemically react with at least one organic polymeric
material generating bigger molecules and optionally even creating a
polymeric network.
[0064] Preferably, the cross-linking of the ionomeric or nearly
ionomeric copolymeric material(s) is in many embodiments performed
without any addition or without any substantial addition of
cross-linkers as typically used for chemical cross-linking by
heating to higher temperatures e.g. in the range from 100 to
300.degree. C. with compounds like such on the base of isocyanate,
isocyanurate or melamine, but only or mostly with any constituent
C). But there may occur some embodiments where the ionomeric or
nearly ionomeric polymeric material is going to be cross-linked or
is at least to a certain content cross-linked with at least one low
temperature corrosion inhibiting cross-linking agent like any
constituent C) and the further organic film-forming
polymer/copolymer/blockcopolymer A') is going to be cross-linked or
is at least to a certain content cross-linked with at least one
cross-linker as typically used for chemical cross-linking by
heating to higher temperatures, e.g. on the base of isocyanate,
isocyanurate or melamine. In such prepared coating, there may be
mixed a certain content of the different types of cross-linkers
that are not clearly coordinated to the type of the
copolymeric/polymeric material A) respectively A') in the
microscale as a fine distribution or even certain homogenization of
the different constituents in the coatings is intended.
[0065] The content of water in the aqueous composition may be
varied in broad ranges, preferably varied in the range from 400 to
950 g/L, more preferred in the range from 450 to 930 g/L, much more
preferred in the range from 500 to 910 g/L, most preferred in the
range from 550 to 900 g/L, especially in the range from 600 to 850
g/L, especially of about 550 g/L, of about 600 g/L, of about 650
g/L, of about 700 g/L, of about 750 g/L, of about 800 g/L, of about
850 g/L or of about 900 g/L or in any ranges in between any of
these data. Preferably, the water added is preferably added as
deionized water or as tap water if it is of low hardness.
[0066] If the aqueous composition according to the invention would
not have any chromium content this solution or dispersion would
normally be stable for years. If such aqueous compositions would
have a significant chromium content, then its stability may in some
cases be influenced to an early gelling, especially if there is a
high chromium content or a high ratio of chromium to total organic
polymeric material. The higher the total solids' content
respectively the content of organic copolymeric/polymeric
material(s), the less stable may be a solution or dispersion
containing a high chromium content.
[0067] In few cases, the aqueous composition will only consist of
the constituents A) and C) and optionally of A'), B) or both. In
many cases, the aqueous composition will only consist of the
constituents A), C) and one to three different constituents
selected of the constituents a) to j) and optionally of A'), B) or
both. In few cases, the aqueous composition will only consist of
the constituents A), C) and four to six or seldom even more
different constituents selected of the constituents a) to j) and
optionally of A'), B) or both.
[0068] The coating weight of the coatings generated with an aqueous
composition according to the invention are typically in the range
from 0.1 to 20 g/m.sup.2, often in the range from 0.3 to 12
g/m.sup.2 and sometimes in the range 0.6 to 5 g/m.sup.2, especially
of about 0.7 g/m.sup.2, of about 0.8 g/m.sup.2, of about 0.9
g/m.sup.2, of about 1 g/m.sup.2, of about 1.1 g/m.sup.2, of about
1.2 g/m.sup.2, of about 1.3 g/m.sup.2, of about 1.4 g/m.sup.2, of
about 1.5 g/m.sup.2, of about 1.6 g/m.sup.2, of about 1.7
g/m.sup.2, of about 1.8 g/m.sup.2, of about 1.9 g/m.sup.2, of about
2 g/m.sup.2, of about 2.2 g/m.sup.2, of about 2.5 g/m.sup.2 or in
any ranges in between any of these data. The coatings may often
show a coating thickness in the range from 0.2 to 3 .mu.m,
especially in the range from 0.4 to 2.5 .mu.m.
[0069] According to the process of the invention, there may be
further added to the aqueous composition at least one constituent
selected from the group consisting of:
[0070] a) acidic catalyst(s), like phosphorus or sulfur containing
acids like orthophosphoric acid, like any sulfonic acid or like
paratoluol sulfonic acid (PTSA) as well as their corresponding
esters and like carboxylic acids like acetic essig, hydroxyacetic
acid, lactic acid and citric acid,
[0071] b) rheology controlling agent(s) like organic
oligomer(s)/polymer(s), silica, sheet silicatic materials like
clay(s)/bentonite(s) and titanium compound(s), especially like
acrylic or urethane oligomer(s)/polymer(s),
[0072] c) wetting agent(s) like
silane(s)/silanol(s)/siloxane(s)/polysiloxane(s), organic
oligomer(s)/polymer(s), alcohol(s)/glycol(s) and other surface
tension reducing compound(s),
[0073] d) adhesion promoting agent(s) like
silane(s)/silanol(s)/siloxane(s)/polysiloxane(s), phosphorus
containing acids' esters as well as organic polymers that have a
reactive polar group like epoxy groups,
[0074] e) film-forming agent(s) like long-chain alcohols preferably
having a chain length in the range from 4 to 20 C-atoms or
phthalates, more preferred, long-chain glycol(s) like propylene
glycol(s), ester alcohol, glycol ether, butandiol or any
combination of these, that are at least partially able to make the
film more flexible, to cause a lower hardness of the coating and to
improve the adhesion, especially in the deformed areas of the
coating and the substrate,
[0075] f) defoaming agent(s) like short-chain paraffin(s),
alcohol(s), hydrocarbon(s) and silicone(s), that are all nearly or
totally water-insoluble,
[0076] g) UV absorber(s), light stabilizer(s) or both,
[0077] h) further agent(s) like photoinitiators, like antioxidants,
like dyes, like coloring pigments as well as like other types of
cross-linkers and
[0078] j) organic solvent(s) like short-chain
alcohol(s)/glycol(s)/glycol ester(s) like hexanol, diethylene butyl
ester, isopropyl alcohol, butanol, propylene glycol, a
esteralcohol, a glycolether, butandiol and N-methylpyrrolidon.
[0079] Sometimes or often, the same compound added may have the
functions as of more than one compound mentioned above.
[0080] The acidic catalyst(s) of the constituent a) may preferably
be at least one of each of phosphorus or sulfur containing acids
like orthophosphoric acid, like any sulfonic acid, like paratoluol
sulfonic acid (PTSA) as well as their corresponding esters, any tin
containing catalysts, any carboxylic acids like acetic acid,
hydroxyacetic acid, lactic acid and citric acid or any combination
thereof. The content of acidic catalyst(s) in the aqueous
composition may be zero or may preferably be varied in the range
from 0.01 to 10 g/L calculated as the active compounds, more
preferred in the range from 0.03 to 6 g/L, much more preferred in
the range from 0.05 to 3 g/L, most preferred in the range from 0.08
to 0.5 g/L, especially of about 0.1 g/L, of about 0.15 g/L, of
about 0.2 g/L, of about 0.25 g/L, of about 0.3 g/L, of about 0.35
g/L, of about 0.4 g/L or of about 0.45 g/L or in any ranges in
between any of these data.
[0081] If there is no acidic catalyst added, then there will be
often limited performance properties such as chemical resistance
and corrosion resistance of the coating. If there is a too high
addition of the acidic catalyst, then the stability of the aqueous
composition may be affected e.g. by gelling and the coating could
become water-sensitive.
[0082] It has to be taken care that in several cases even a small
amount of any surfactant(s) may affect the stability of the aqueous
composition as well as the coating properties of the coatings
generated from it like the corrosion resistance. Therefore, it is
preferred to avoid all or any effective amount of surfactants.
[0083] The rheology controlling agent(s) of the constituent b) may
preferably be organic oligomer(s)/polymer(s), silica, sheet
silicatic materials like clay(s)/bentonite(s), titanium compound(s)
or any combination of these, especially acrylic or urethane
oligomer(s)/polymer(s). More preferred, the rheology controlling
agent(s) added is an acrylic polymer, a bentonite or silica
nanoparticles or any combination of these. Rheology controlling
agents may preferably be added to increase the coating weight if
necessary. The content of rheology controlling agent(s) in the
aqueous composition may be zero or may preferably be varied in the
range from 0.01 to 10 g/L calculated as the active compounds, more
preferred in the range from 0.03 to 8 g/L, much more preferred in
the range from 0.05 to 5 g/L, most preferred in the range from 0.08
to 2 g/L, especially of about 0.1 g/L, of about 0.2 g/L, of about
0.3 g/L, of about 0.4 g/L, of about 0.5 g/L, of about 0.6 g/L, of
about 0.7 g/L, of about 0.8 g/L, of about 0.9 g/L, of about 1.0
g/L, of about 1.1 g/L, of about 1.2 g/L, of about 1.3 g/L, of about
1.4 g/L, of about 1.5 g/L, of about 1.6 g/L, of about 1.7 g/L, of
about 1.8 g/L or of about 1.9 g/L or in any ranges in between any
of these data.
[0084] If there is no rheology controlling agent added, then there
may occur problems to achieve the coating weight desired. If there
is a too high addition of the rheology controlling agent(s), then
the viscosity of the aqueous composition may be too high and lead
to improper application and flaws in the coating.
[0085] There may be added wetting agent(s) of the constituent c)
like silane(s)/silanol(s)/siloxane(s)/polysiloxane(s), organic
oligomer(s)/polymer(s), alcohol(s)/glycol(s), other surface tension
reducing compound(s) or any combination thereof. Preferably, the
wetting agent(s) added may be at least one compound on the base of
polysiloxanes, acrylics, long-chain compounds like glycols,
polyglycols, succinic acid, sulfosuccinic acid or any combination
thereof. The content of wetting agent(s) in the aqueous composition
may be zero or may preferably be varied in the range from 0.01 to
10 g/L calculated as the active compounds, more preferred in the
range from 0.03 to 8 g/L, much more preferred in the range from
0.06 to 5 g/L, most preferred in the range from 0.1 to 2 g/L,
especially of about 0.3 g/L, of about 0.5 g/L, of about 0.8 g/L, of
about 1.1 g/L or of about 1.5 g/L or in any ranges in between any
of these data. Wetting agents may preferably be added to the
aqueous composition if there is a metallic surface used that is
hard to wet, e.g. as it is very smooth. If there is no wetting
agent added, then the film quality may be affected by voids,
striations and partial wetting of the metallic surface. If there is
a too high addition of the wetting agent(s), then the coating may
be too water-sensitive.
[0086] The adhesion promoting agent(s) of the constituent d) may
preferably be silane(s)/silanol(s)/siloxane(s)/polysiloxane(s),
phosphorus containing acids' esters and organic polymers that have
a reactive polar group like epoxy groups or any combination of
these. Preferably, the adhesion promoting agent(s) added is
isopropyl alcohol, propylene glycol, butyl benzol phthalate or any
combination of these. Preferably, the at least one adhesion
promoting agent added is at least one compound selected from the
group of silanes/siloxanes/polysiloxanes or any compound derived
from it or any combination of these. The content of adhesion
promoting agent(s) in the aqueous composition may be zero or may
preferably be varied in the range from 0.01 to 10 g/L calculated as
the active compounds, more preferred in the range from 0.03 to 8
g/L, much more preferred in the range from 0.05 to 5 g/L, most
preferred in the range from 0.08 to 2 g/L, especially of about 0.1
g/L, of about 0.2 g/L, of about 0.3 g/L, of about 0.4 g/L, of about
0.5 g/L, of about 0.6 g/L, of about 0.7 g/L, of about 0.8 g/L, of
about 0.9 g/L, of about 1.0 g/L, of about 1.1 g/L, of about 1.2
g/L, of about 1.3 g/L, of about 1.4 g/L, of about 1.5 g/L, of about
1.6 g/L, of about 1.7 g/L, of about 1.8 g/L or of about 1.9 g/L or
in any ranges in between any of these data.
[0087] Adhesion promoting agent(s) d) may be needed if there is a
certain content of at least one further organic polymer/copolymer
participating for the rest of the total organic polymeric material
as constituent A'), their corresponding
oligomers/cooligomers/monomers/comonomers or any combination
thereof. Adhesion promoting agents may be further on added to
correct the adhesion properties if there would be a further layer
applied to the organic coating according to the invention which may
cause problems by sticking. If there is no adhesion promoting agent
added, then there may occur a loss of adhesion of the organic
coating to the metallic surface or the adhesion to the succeeding
paint layer. If there is a too high addition of the adhesion
promoting agent(s), then this may affect the film integrity.
[0088] The film-forming agent(s) of the constituent e) may
preferably be at least one long-chain alcohol like long-chain
glycols as well as like phthalates, preferably like propylene
glycols, ester alcohols, glycol ethers, propylene glycols, glycol
ethers, butandiol, isopropyl alcohol, dibutyl phthalate, butyl
benzol phthalate or any combination of these. They may preferably
be added to make the coating more flexible, to cause a lower
hardness of the coating and to improve its adhesion, especially in
the deformed areas of the coating and the substrate. The long-chain
alcohols, especially such with 4 to 20 C-atoms, may be selected
from the group consisting of butandiols, butylglycols,
butyidiglycols, ethylene glycolethers like ethylene
glycolmonobutylether, ethylene glycolmonoethylether, ethylene
glykolmonomethylether, ethylglycolpropylether, ethylene
glycolhexylether, diethylene glycolmethylether, diethylene
glycolethylether, diethylene glycolbutylether, diethylene
glycolhexylether or polypropylene glycolethers like propylene
glycolmonomethylether, dipropylene glycolmonomethylether,
tripropylene glycolmonomethylether, propylene glycolmonobutylether,
dipropylene glycolmonobutylether, tripropylene
glycolmonobutylether, propylene glycolmonopropylether, dipropylene
glycolmonopropylether, tripropylene glycolmonopropylether,
propylene glycolphenylether, trimethylpentandioldiisobutyrat,
polytetrahydrofurans, polyetherpolyols and polyesterpolyols.
Film-forming agent(s) e) may sometimes be needed if there is a
certain content of at least one further organic film-forming
polymer/copolymer/blockcopolymer A') or their corresponding
oligomers/cooligomers/monomers/comonomers like any acrylic or epoxy
or urethane containing resin not being an ionomeric resin,
participating for the rest of the total organic polymeric material
to 100% by weight. Film-forming agents may preferably be used, when
there is added a further organic polymeric material. They may
function as a cosolvent. The content of film-forming agent(s) in
the aqueous composition may be zero or may preferably be varied in
the range from 0.05 to 50 g/L calculated as the active compounds,
more preferred in the range from 0.1 to 30 g/L, much more preferred
in the range from 0.3 to 10 g/L, most preferred in the range from
0.5 to 3 g/L, especially of about 0.6 g/L, of about 0.7 g/L, of
about 0.8 g/L, of about 0.9 g/L, of about 1.0 g/L, of about 1.1
g/L, of about 1.2 g/L, of about 1.3 g/L, of about 1.4 g/L, of about
1.5 g/L, of about 1.6 g/L, of about 1.7 g/L, of about 1.8 g/L, of
about 1.9 g/L, of about 2.0 g/L, of about 2.1 g/L, of about 2.2
g/L, of about 2.3 g/L, of about 2.4 g/L, of about 2.5 g/L, of about
2.6 g/L, of about 2.7 g/L, of about 2.8 g/L or of about 2.9 g/L or
in any ranges in between any of these data.
[0089] The defoaming agent(s) of the constituent f) may preferably
be short-chain paraffin(s), alcohol(s) hydrocarbon(s) and
silicone(s) or any combination thereof that are all
water-insoluble. Preferably, the defoaming agent(s) added is an
aliphatic hydrocarbon, silica-modified aliphatic hydrocarbon,
high-molecular weight alcohols or any combination of these. The
content of further agent(s) like defoaming agent(s) in the aqueous
composition may be zero or may preferably be varied in the range
from 0.01 to 10 g/L calculated as the active compounds, more
preferred in the range from 0.03 to 8 g/L, much more preferred in
the range from 0.05 to 5 g/L, most preferred in the range from 0.08
to 2 g/L, especially of about 0.1 g/L, of about 0.2 g/L, of about
0.3 g/L, of about 0.4 g/L, of about 0.5 g/L, of about 0.6 g/L, of
about 0.7 g/L, of about 0.8 g/L, of about 0.9 g/L, of about 1.0
g/L, of about 1.1 g/L, of about 1.2 g/L, of about 1.3 g/L, of about
1.4 g/L, of about 1.5 g/L, of about 1.6 g/L, of about 1.7 g/L, of
about 1.8 g/L or of about 1.9 g/L or in any ranges in between any
of these data.
[0090] If there is no defoaming agent f) added, then the foam
generated may be disturbing or the possibility of forming a
homogeneous and flexible coating showing integrity and lacking
voids is reduced or both may occur; there may be even an easily
fractured coating. If there is a too high addition of the defoaming
agent(s), then this may cause voids in the coating.
[0091] There may be added at least one further agent of the
constituent g) may preferably be at least one UV absorber, at least
one light stabilizer or any other kind of at least one cross-linker
or any combination of these--not preventing any further agent
having any function not yet mentioned to be further added in an
amount of up to 0.5 g/L each. The content of UV absorber(s) or of
light stabilizer(s) or of both in the aqueous composition may be
zero or may preferably be varied in the range from 0.01 to 10 g/L
calculated as the active compounds, more preferred in the range
from 0.03 to 6 g/L, much more preferred in the range from 0.05 to 4
g/L, most preferred in the range from 0.08 to 2.0 g/L, especially
of about 0.1 g/L, of about 0.2 g/L, of about 0.3 g/L, of about 0.4
g/L, of about 0.5 g/L, of about 0.6 g/L, of about 0.7 g/L, of about
0.8 g/L, of about 0.9 g/L, of about 1.0 g/L, of about 1.1 g/L, of
about 1.2 g/L, of about 1.3 g/L, of about 1.4 g/L, of about 1.5
g/L, of about 1.6 g/L, of about 1.7 g/L, of about 1.8 g/L or of
about 1.9 g/L or in any ranges in between any of these data. Such
agents may help to protect the organic coating not to be affected
by energy-rich light and to keep the colors and clearness of the
coating.
[0092] There may be added at least one further agent of the
constituent h) like at least one compound selected from the group
consisting of photoinitiators, antioxidants, dyes, coloring
pigments and other types of cross-linkers than the low temperature
corrosion inhibiting cross-linking agents C). An antioxidant may
help to avoid the early coloration e.g. into yellow colors and the
early destruction of a coating if a coating should be heated up to
a higher temperature, e.g. for about one hour at a temperature in a
range of from 120 to 200.degree. C. The dyes or pigments or both
shall help to make the coating better visible or even colored. The
pigments are preferably very fine, more preferred having a mean
particle diameter of less than 1 .mu.m.
[0093] The content of photoinitiators, antioxidants, other types of
cross-linkers or any combination thereof h) in the aqueous
composition may be zero or may preferably be varied in the range
from 0.01 to 50 g/L calculated as the active compounds, more
preferred in the range from 0.03 to 40 g/L, much more preferred in
the range from 0.05 to 30 g/L, most preferred in the range from
0.08 to 20 g/L, especially of about 0.1 g/L, of about 0.2 g/L, of
about 0.3 g/L, of about 0.4 g/L, of about 0.5 g/L, of about 0.6
g/L, of about 0.7 g/L, of about 0.8 g/L, of about 0.9 g/L, of about
1.0 g/L, of about 1.1 g/L, of about 1.2 g/L, of about 1.3 g/L, of
about 1.4 g/L, of about 1.5 g/L, of about 1.6 g/L, of about 1.7
g/L, of about 1.8 g/L or of about 1.9 g/L or in any ranges in
between any of these data. Typically, if there is a content of a
high temperature cross-linker, then its content is typically very
high. Such agents may help to cross-link the organic
copolymeric/polymeric material(s) A) or A') or both chemically or
physically or both.
[0094] The content of all constituents a) to h) except the content
of high temperature cross-linkers altogether present in the aqueous
composition may be varied in broad ranges. If this content is not
zero, it is preferably varied in the range from 0.01 to 80 g/L,
more preferred in the range from 0.05 to 60 g/L, much more
preferred in the range from 0.1 to 40 g/L, most preferred in the
range from 0.5 to 30 g/L, especially in the range from 0.8 to 22
g/L or in the range from 1 to 14 g/L, especially of about 1 g/L, of
about 2 g/L, of about 3 g/L, of about 4 g/L, of about 5 g/L, of
about 6 g/L, of about 7 g/L, of about 8 g/L, of about 9 g/L, of
about 10 g/L, of about 11 g/L, of about 12 g/L, of about 13 g/L, of
about 14 g/L, of about 15 g/L, of about 16 g/L, of about 17 g/L, of
about 18 g/L, of about 19 g/L, of about 20 g/L, of about 21 g/L or
of about 22 g/L or in any ranges in between any of these data.
[0095] The organic solvent(s) of the constituent j) may preferably
be short-chain alcohol(s)/glycol(s)/glycol ester(s) like hexanol,
propylene glycol, an esteralcohol, a glycolether, diethylene butyl
ester, ethanol, butanol, isobutanol, secondary butanol, propanol,
isopropanol, butandiol, N-methylpyrrolidon or any combination
thereof. Preferably, an organic solvent is only added if it is
needed for at least one other constituent present in the aqueous
composition or added to any raw material. The content of organic
solvent(s) in the aqueous composition may be zero or may preferably
be varied in the range from 0.1 to 250 g/L calculated as the
compound, more preferred in the range from 0.5 to 200 g/L, much
more preferred in the range from 2 to 150 g/L, most preferred in
the range from 10 to 100 g/L, especially of about 25 g/L, of about
40 g/L, of about 55 g/L, of about 70 g/L or of about 85 g/L or in
any ranges in between any of these data. More preferred, the
organic solvent(s) added may be ethanol, butanol, isobutanol,
secondary butanol, propanol, isopropanol or any combination of
these.
[0096] According to the process of the invention, the coating may
be dried at any temperature, but may preferably be dried at a
temperature in the range from 1 to 98.degree. C., more preferred in
the range from 5 to 80.degree. C., even more preferred in the range
from 8 to 65.degree. C., most preferred in the range from 10 to
50.degree. C., especially in the range from 12 to 35.degree. C. or
in the range from 14 to 30.degree. C. or in the range from 15 to
28.degree. C., even at about room temperature. In some cases, it is
quite sufficient to let the wet film of the aqueous composition be
dried at about room temperature or at a temperature of about
30.degree. C. Many compositions according to the invention do not
require any heating to cross-link the constituents of the generated
coating. In some cases, there may be a heating in the range of up
to 80.degree. C., sometimes to enhance the cross-linking of the
organic copolymeric/polymeric material(s). Nevertheless, if there
would be a heating to higher temperatures than 80.degree. C., this
is not necessary, but will normally not affect the properties of
the coating, but sometimes even improve them. Instead of only one
drying there may be a drying, even perhaps at a lower temperature,
and then a heating or any similar process, whereby the at least one
heating may preferably be used for the content of the other organic
polymeric material A') present in the composition and which may
need a high temperature like for chemical cross-linking. There may
be even a higher heating for any other purpose.
[0097] According to the process of the invention, the coating
generated with the aqueous composition on the metallic component is
afterwards coated with at least one layer each of a primer, a
powder paint, a base coat, a clear coat, an adhesive or any
combination of these, whereby these coatings may be performed
before or after any forming operation.
[0098] According to the process of the invention, the coating
generated with the aqueous composition may in some embodiments has
the function of a pretreatment primer this means that there is no
pretreatment layer rendering corrosion resistance and paint
adhesion under the organic coating generated with the aqueous
composition according to the invention. This is possible, as it
needs in many cases no classical pretreatment layer like a zinc
phosphate layer, an alkali metal phosphate layer or a chromate
layer. Then, at least one process step and at least one coating are
saved.
[0099] According to the process of the invention, there may
preferably be applied a coating of any composition containing at
least one forming agent like any oil or wax or both on the coating
prepared with the aqueous composition according to the invention
whereby the such coated metallic component may be used for a heavy
forming operation like deep-drawing.
[0100] According to the process of the invention, the coating
generated with the aqueous composition may preferably be joined by
the aid of at least one adhesive with any paper, any foil, any
sheet or any other part. Preferably, a polyurethane foam or a
paste, an ink, a solution or a dispersion of a silicone adhesive, a
starch adhesive, an acrylic adhesive, an epoxy adhesive, a
polysulfide adhesive or of a polyurethane adhesive may be used as
an adhesive or any combination of these.
[0101] The aqueous compositions according to the invention may be
used to coat metallic components like coils, sheets, plates, foils,
plastic laminated metal foils, other laminated components, parts of
any shape, wires or any combination of these to generate organic
coatings with a high flexibility and high resistance against
corrosion. Such compositions may be used for the production e.g. of
corrugated iron, gutters, profiles, tubings, automotive stampings,
housings, electronic equipment or guard rails. Such components may
be used for inside and outside architectural use, aerospace
industry, automotive industry, apparatuses, appliance industry,
construction, roofing, siding, transport, ventilating, cylinders,
fasteners, shafts, containers or tanks.
[0102] It was astonishing that the very thin organic coatings that
have often a coating thickness in the range from 0.2 to 3 .mu.m or
even in the range from 0.5 to 2.5 .mu.m show such excellent
corrosion protection results as well as such excellent wear
resistance although the coefficient of friction is in the range of
about 0.2 which is well adapted to industrial uses.
[0103] It was further astonishing that such organic coatings are of
an excellent formability even without using waxes and without using
oils as constituents in the aqueous composition used for the
coating or as a further layer on the coating.
[0104] Further on, it succeeded to significantly reduce the raw
materials costs as well as the process costs by lowering the heat
and temperature for drying or in some cases even by avoiding any
heating for the drying or any other heating or both.
[0105] The method of production of metallic components coated with
an aqueous composition according to the invention is significantly
easier than with the aqueous compositions of the state of the art
for coatings of similar use. The metallic components coated with an
aqueous composition according to the invention allow an optimized
forming operation without an increase of forces, of the coefficient
of friction and of wear.
[0106] It succeeded to avoid or reduce the content of chromium
containing compounds in a significant extent without loosing the
excellent properties of the coatings according to the
invention.
[0107] It is the first time according to the knowledge of the
inventors that such an organic composition to be used for very thin
organic coatings having a coating thickness of below 3 or of below
2.5 .mu.m is described that is in some embodiments free or nearly
free of any chromium compounds or even containing up to 10 g/L of
chromium containing compounds calculated as CrO.sub.3 and that may
be cross-linked or homogenously filmed at temperatures below
50.degree. C.
EXAMPLES AND COMPARISON EXAMPLES
[0108] The examples and comparison examples described in the
following are intended to elucidate the subject-matter of the
invention in more detail. The specified concentrations and
compositions relate to the aqueous composition as used in the bath
or as added to the bath or both and must not be identical with the
initial solutions/dispersions of mostly higher concentrations
(concentrates) or with the replenishing solutions/dispersions to
replenish the consumption of chemical constituents in the bath. The
addition of several constituents was in such constitution that some
of the raw materials added showed a certain content of water or
organic solvent or both that was recalculated.
[0109] Commercially available steel panels of cold rolled steel
(CRS), of hot dip galvanized steel (HDG) and of Galvalume.RTM. (55%
AlZn) were used for the following experiments and tests.
[0110] First, the CRS panels were degreased in an alkaline spray
cleaner. Then, all kinds of steel panels as mentioned above were
treated with the aqueous composition according to the invention as
shown in table 2. In this treatment, a defined quantity of the
aqueous composition (bath solution/dispersion) was applied in such
a way with the aid of a roll coater that a wet film thickness of
about 4 mg/m.sup.2 arose. The aqueous composition was applied at a
temperature of about 20.degree. C. with a velocity of about 20
m/min. Subsequently, the wet film was dried at a temperature of
about 65.5.degree. C. (150 F) PMT (peak-metal-temperature) which
needs about 140.degree. C. of a laboratory convection oven for 25
seconds of time in the oven. The dry films (the coatings) showed a
coating weight of about 8 to 12 mg/m.sup.2. TABLE-US-00001 TABLE 1
Composition and properties of the different raw materials used: EAA
= ethylene acrylic acid, C = low temperature corrosion inhibiting
agent Amount in g/L Composition and approximate data of properties:
EMAA1 ethylene methacrylic acid copolymer based dispersion EAA1
ethylene acrylic copolymer based dispersion, melting point
75.degree. C., melt index 1300, molecular weight 6000, T.sub.g
about -8.degree. C. EAA2 ethylene acrylic copolymer based
dispersion, melting point 77.degree. C., melt index 300, molecular
weight 8000, T.sub.g about -8.degree. C. PUAR polyurethane acrylic
acid copolymer based dispersion AR1 acrylic resin with T.sub.g of
16.degree. C. and an acid number of about 30 AR2 acrylic resin with
T.sub.g of 35.degree. C. and an acid number of about 30
Neutralizing NH.sub.4OH Agent1 Neutralizing alkanolamine Agent2 C1
ammonium dichromate C2 ammonium zirconium carbonate C3 TiO.sub.2
nanoparticles C4 K.sub.2CrO.sub.3 Add1 oxidized polyethylene wax
Add2 nanoparticles of SiO.sub.2 DI Water deionized water Catalyst
PTSA wetting agent polysiloxane adhesion epoxysilane promoting
agent Defoamer aliphatic hydrocarbon UV-Absorber benzotriazole
light stabilizer hindered amine
[0111] TABLE-US-00002 TABLE 2 Composition of the bath liquids of
inventive examples B of comparison examples VB: EAA = ethylene
acrylic acid, C = low temperature corrosion inhibiting agent,
concentration data in g per liter Example/Comp. Ex. E1 E2 E3 E4 E5
E6 E7 E8 E9 E10 E11 E12 E13 E14 Amount in g/L: EMAA1 240.0 100.0
EAA1 130.0 230.0 240.0 120.0 EAA2 120.0 192.0 200.0 200.0 240.0
240.0 192.0 230.0 242.0 240.0 AR1 40.0 AR2 40.0 Neutralizing Agent
1 24.0 24.0 24.0 24.0 24.0 30.0 20.0 20.0 24.0 19.0 23.0 24.0 30.0
Neutralizing Agent 2 24.0 C1 10.0 20.0 20.0 10.0 10.0 8.0 10.0 10.0
10.0 10.0 8.0 8.0 10.0 C4 20.0 Catalyst 0.1 0.1 0.1 0.1 0.1 0.1 0.1
0.1 0.1 0.1 0.1 0.1 0.1 0.1 Wetting agent 3.0 3.0 3.0 3.0 3.0 3.0
3.0 3.0 3.0 3.0 3.0 3.0 3.0 Defoamer 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 1.0 1.0 1.0 1.0 1.0 1.0 UV-Absorber 1.0 1.0 1.0 1.0 1.0 1.0 1.0
1.0 1.0 1.0 1.0 1.0 1.0 Light Stabilizer 1.0 1.0 1.0 1.0 1.0 1.0
1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Sum without DI-water 280.1 280.1
276.1 280.1 280.1 236.1 276.1 276.1 280.1 280.1 225.1 279.1 280.1
286.1 DI-Water 719.9 719.9 723.9 719.9 719.9 763.9 723.9 723.9
719.9 719.9 774.9 720.9 719.9 713.9 Solid's content g/L 250 250 250
250 250 200 250 250 250 250 200 250 250 250 Solid's content 25 25
25 25 25 20 25 25 25 25 20 25 25 25 weight % Storage stability (gel
VG VG VG VG VG G VG VG VG VG VG VG VG Gel effect) Stable
composition Y Y Y Y Y HV Y Y Y Y Y Y Y N pH-value 8.2 8.2 8.2 8.2
8.2 9.5 8.2 8.2 8.2 8.2 8.2 8.2 8.2 9.5 Drying temperature 65 65 65
65 65 65 65 65 65 65 65 65 65 -- p.m.t. .degree. C. Dry film
coating 1.2 1.2 1.2 1.2 1.2 1.0 1.2 1.2 1.2 1.2 1.0 1.2 1.2 --
weight, g/m.sup.2 Visual appearance Br Br BR Br Br Br Br Br Br Br
Br Br Br -- Corrosion resistance without additional paint:
Salt-spray ASTM 2 0 0 2 5 5 0 0 5 0 5 0 2 -- B117 240 h, % corr.
Salt-spray ASTM 5 0 0 5 5 10 2 2 10 2 20 5 5 -- B117 480 h, % corr.
Wet stack test, % OK OK OK OK OK 10 OK OK 10 OK 15 OK OK -- face
corrosion Outdoor exposure NDC NDC LDC NDC NDC NDC NDC NDC NDC NDC
NDC NDC NDC -- after 1 year Pin-on-disc test: Friction coefficient
0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 -- Revolutions
until >150 >150 >150 >150 >150 50 120 120 >150
>150 50 >150 >150 -- obtaining 0.4 friction Corrosion
resistance and paint adhesion with polyester based powder paint:
Salt-spray ASTM 4 4 4 5 5 7 3 4 5 4 10 4 4 B117 480 h creepage on
scribe, mm Cross hutch before GT1 GT1 GT1 GT1 GT1 GT1 GT1 GT1 GT1
GT1 GT1 GT1 GT1 -- humidity test, grade Cross hutch after 480 GT1
GT1 GT1 GT1 GT1 GT3 GT1 GT1 GT1 GT1 GT3 GT1 GT1 -- h humidity test,
grade Example/Comp. Ex. E15 E16 E17 E18 E19 E20 E21 E22 E23 CE1 CE2
CE3 CE4 Amount in g/L: EAA2 235.0 288.4 210.0 240.0 238.0 235.0
170.0 250.0 235.0 70.0 PUAR 110.0 80.0 AR1 116.0 80.0 98.0 88.0 AR2
40.0 88.0 Neutralizing Agent 1 23.0 28.0 21.0 25.0 25.0 25.0 17.0
25.0 30.0 3.0 3.0 6.0 3.0 C1 15.0 11.6 10.0 10.0 15.0 15.0 10.0 C2
40.0 40.0 15.0 20.0 20.0 20.0 C3 2.0 Additive 1 14.0 14.0 14.0 14.0
Additive 2 48.0 48.0 48.0 Catalyst 0.1 0.1 0.1 0.1 0.1 0.1 Wetting
agent 3.0 3.0 Defoamer 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 3.0
UV-Absorber 1.0 1.0 2.0 2.0 2.0 2.0 Light Stabilizer 1.0 1.0 Sum
without DI-water 279.1 334.1 274.0 276.1 276.1 278.1 270.0 293.1
281.0 256.0 253.0 256.0 253.0 DI-Water 720.9 665.9 726.0 723.9
723.9 721.9 730.0 706.9 719.0 744.0 747.0 744.0 747.0 Solid's
content g/L 250 300 250 250 250 250 250 265 250 250 250 250 250
Solid's content 25 30 25 25 25 25 25 26.5 25 25 25 25 25 weight %
Storage stability (gel VG G VG VG VG VG VG VG Gel VG VG VG VG
effect) Stable composition Y HV Y Y Y Y Y Y N Y Y Y Y pH-value 8.2
8.2 8.2 8.2 8.2 8.2 8.2 8.2 9.2 8.2 8.2 8.2 8.2 Drying temperature
65 65 65 65 65 65 65 65 -- 65 65 65 65 p.m.t. .degree. C. Dry film
coating 1.2 1.4 1.2 1.2 1.2 1.2 1.2 1.3 -- 1.2 1.2 1.2 1.2 weight,
g/m.sup.2 Visual appearance Br Br Br Br Br Br Br Br -- Br Br Br Br
Corrosion resistance without additional paint: Salt-spray ASTM 0 0
0 0 0 0 0 0 -- 0 0 0 0 B117 240 h, % corr. Salt-spray ASTM 0 0 5 5
5 0 5 5 -- 0 0 5 2 B117 480 h, % corr. Wet stack test, % OK OK OK
OK OK OK OK OK -- OK OK OK OK face corrosion Outdoor exposure NDC
NDC NDC LDC LDC NDC NDC NDC -- LDC LDC LDC LDC after 1 year
Pin-on-disc test: Friction coefficient 0.2 0.2 0.2 0.2 0.2 0.2 0.2
0.2 -- 0.17 0.17 0.17 0.17 Revolutions until >150 >150
>150 >150 >150 >150 120 >150 -- 10 20 100 30
obtaining 0.4 friction Corrosion resistance and paint adhesion with
polyester based powder paint: Salt-spray ASTM 3 3 4 4 4 3 4 4 -- 3
4 4 4 B117 480 h creepage on scribe, mm Cross hutch before GT1 GT1
GT1 GT1 GT1 GT1 GT1 GT1 -- GT1 GT1 GT1 GT1 humidity test, grade
Cross hutch after 480 GT1 GT1 GT1 GT1 GT1 GT1 GT1 GT1 -- GT1 GT1
GT1 GT1 h humidity test, grade List of abbreviations as used in
table 2: Storage stability: VG = very good, G = good, Gel = gelled
Stability of the composition: Y = yes, N = no, HV = high viscosity
(upper end) Visual appearance: Br = bright, this means: not yellow
and okay NDC = no discoloration, LDC = low discoloration Tests: F =
failed, P = passed, Ok = okay, Blank fields: No panels, no
results.
[0112] Only the non-gelled compositions were applied on the
metallic sheets by using a bar-coater which offers a dry film in
the range of about 1 to 2 g/m.sup.2 depending on the concentration
of the aqueous composition, mostly using 25% by weight of solid's
content. If the solid's content is lower then the dry film
thickness is lower, too. After the drying, the coated panels were
inspected and tested.
[0113] Then, the forming operations were undertaken by the forming
tests as listed in table 2: The friction and wear characteristics
were tested with the pin-on-disc test. This test enables to check
the friction coefficient and its change during mechanical attack by
a high number of revolutions of a ball on the coated sheet
necessary to obtain a friction coefficient of 0.4 with the help of
a pin-on-disc apparatus. The pin-on-disc test correlates well with
forming procedures in production having 5 to 20 steps of singular
formings in succession. The test results are excellent as there is
a practically constant wear and friction behavior after the
starting period which keeps typically the friction coefficient at
about 0.2. More than 150 revolutions characterize a coating that is
extremely stable and provides an excellent forming effect. The
organic coatings having a content of a wax additive as well as only
other organic polymeric materials A') not being ionomeric
copolymeric materials A) show a relatively low coefficient of
friction, but a very high wear and a very low wear resistance in
the pin-on-disc test (comparison examples CE1, CE2 and CE4). The
comparison example having a content of the wax additive Additive 1,
of a portion of ionomeric copolymeric materials A) as well as a
dominant portion of other organic polymeric materials A') show a
low wear, this means a high wear resistance (CE3), but the
corrosion resistance is a bit lowered and the costs of the aqueous
composition are quite high as only 42% of the film-forming
constituents are ionomeric copolymeric materials of low costs.
[0114] The following tests are performed exactly as described in
the standards. The corrosion tests on not post-painted surfaces
were are conducted by measuring the face corrosion percentage.
Concerning the corrosion resistance, there are significant
differences in the performance especially of the salt-spray test
after 240 hours respectively after 480 hours, measured as % face
corrosion. All the corrosion tests with coatings having a certain
content of chromate exhibit an excellent corrosion resistance. The
chromate-free coatings that have a content of the zirconium
carbonate have a very good corrosion resistance. Coatings of a low
chromate content may have a reason for a less good corrosion test
result, e.g. by a content of another neutralizing agent. It has now
been found that the ionomeric materials are superior in corrosion
resistance to other organic polymeric materials if there is a
certain temperature as they have a melt release effect which closes
the coating again after a defect has been generated in the coating.
The wet stack test is performed according to a Chemetall internal
standard. In the wet stack test, ten sheets coated on both sides
without protection of the cut edges of 100 to 100 mm size are
stacked after having put a drop of DI water of about 1 ml in the
middle of every coated surface. This stack of coated sheets is
totally wrapped in a polyethylene foil and is exposed over four
weeks in a humidity cabinet which runs at 100% of humidity at
40.degree. C.
[0115] The paint adhesion tests on the post-painted surfaces--the
salt-spray test on the scribe and the cross hutch test before and
after the humidity test according to DIN 50017 KK--are performed
after painting the coated panels with a polyester based powder
paint of about 50 .mu.m coating thickness that was sintered at
about 218.degree. C. If the salt-spray test on the scribe shows 3
or 4 and if the cross hutch test after the humidity test shows GT1,
the requirements of the appliance industry are well met. Nearly all
coatings show a good paint adhesion.
[0116] Further on, it was found that the film-forming temperature
is significantly lower than for the most other organic polymeric
materials and that there may be a certain self-healing effect for
defects and that a denser film may be generated than with the most
other organic polymeric materials.
[0117] It has further been found that the addition of a UV
absorbing agent reduces significantly the coloration of such
organic coatings under sun light exposure (long-term outdoor
exposure).
[0118] The coatings generated according to the invention show a
relatively low permeability, are dense, of low affectability and of
good homogeneity. They reach a relatively high cross-linking degree
although there are not used any high temperature cross-linkers
added as on the base e.g. of isocyanates.
* * * * *