U.S. patent application number 13/507981 was filed with the patent office on 2013-02-14 for treating fluidic channels.
This patent application is currently assigned to Aculon, Inc.. The applicant listed for this patent is Eric L. Bruner, Eric L. Hanson. Invention is credited to Eric L. Bruner, Eric L. Hanson.
Application Number | 20130037161 13/507981 |
Document ID | / |
Family ID | 47676771 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130037161 |
Kind Code |
A1 |
Hanson; Eric L. ; et
al. |
February 14, 2013 |
Treating fluidic channels
Abstract
Disclosed is the treatment of the interior walls of a fluidic
channel with a self-assembled monolayer of an organophosphorus
acid.
Inventors: |
Hanson; Eric L.; (Carlsbad,
CA) ; Bruner; Eric L.; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hanson; Eric L.
Bruner; Eric L. |
Carlsbad
San Diego |
CA
CA |
US
US |
|
|
Assignee: |
Aculon, Inc.
San Diego
CA
|
Family ID: |
47676771 |
Appl. No.: |
13/507981 |
Filed: |
August 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61574935 |
Aug 11, 2011 |
|
|
|
Current U.S.
Class: |
138/145 ;
427/230; 427/239 |
Current CPC
Class: |
B05D 7/222 20130101;
F16L 58/08 20130101; B82Y 30/00 20130101; B82Y 40/00 20130101; B05D
1/185 20130101; B05D 2202/00 20130101 |
Class at
Publication: |
138/145 ;
427/230; 427/239 |
International
Class: |
B05D 7/22 20060101
B05D007/22; F16L 9/00 20060101 F16L009/00 |
Claims
1. A method of depositing a thin coating of nanometer dimensions
within a fluidic channel comprising: (a) contacting interior walls
of the fluidic channel either directly or indirectly through an
intermediate organometallic coating with a an organophosphorus
acid, (b) forming a self-assembled monolayer of the
organophosphorus acid adhered to the interior walls of the fluidic
channel or to the intermediate organometallic layer.
2. The method of claim 1 in which the fluidic channel is a closed
fluidic circuit.
3. The method of claim 1 in which the fluidic channel is an open
fluidic channel.
4. The method of claim 3 in which the open fluidic channel is
associated with a dispensing device.
5. The method of claim 2 in which the open fluidic channel is
associated with a radiator.
6. The method of claim 1 in which the fluidic channel is made from
metal.
7. The method of claim 6 in which the fluidic channel is made from
iron.
8. The method of claim 6 in which the metal is a metal alloy.
9. The method of claim 6 in which the metal alloy is stainless
steel.
10. The method of claim 6 in which the self-assembled monolayer is
chemically bonded to the metal.
11. The method of claim 1 in which the organophosphorus acid is
contacted with the intermediate organometallic layer.
12. The method of claim 1 in which the organometallic layer is a
polymeric metal oxide having unreacted alkoxide and/or hydroxyl
groups.
13. The method of claim 12 in which the substrate is a polymeric
material.
14. The method of claim 13 in which the self-assembled monolayer is
chemically bonded to the organometallic layer.
15. The method of claim 1 in which the organophosphorus acid is an
organophosphonic acid.
16. The method of claim 15 in which the organophosphorus acid is an
organophosphonic acid or derivative thereof comprising a compound
or a mixture of compounds of the structure: ##STR00007## wherein x
is 0 to 1, y is 1, z is 1 to 2 and x+y+z=3; R and R'' are each
independently a hydrocarbon or substituted hydrocarbon radical
having a total of 1 to 30 carbon atoms or an oligiomeric group, R'
is H, a metal or lower alkyl.
17. The method of claim 16 where R and R'' are each independently a
fluorine-substituted hydrocarbon radical.
18. The method of claim 16 in which R and/or R'' is a group of the
structure: ##STR00008## where A is an oxygen radical or a chemical
bond; n is 1 to 6; Y is F or .sub.C.sub.nF.sub.2n+1; b is 2 to 20,
m is 0 to 6 and p is 0 to 18.
19. A fluidic channel having interior walls with a self-assembled
monolayer of an organophosphorus acid adhered directly or through
an intermediate organometallic coating to the interior walls.
20. The fluidic channel of claim 19, which is a closed fluidic
circuit.
21. The fluidic channel of claim 19, which is an open fluidic
channel.
22. The fluidic channel of claim 21 in which the open fluidic
channel is associated with a dispensing device.
23. The fluidic channel of claim 20, which is associated with a
radiator.
24. The fluidic channel of claim 19, which is made from metal.
25. The fluidic channel of claim 24, which is made from iron.
26. The fluidic channel of claim 24, which is a metal alloy.
27. The fluidic channel of claim 24, which is stainless steel.
28. The fluidic channel of claim 19 in which the self-assembled
monolayer is chemically bonded to the metal.
29. The fluidic channel of claim 19 in which the organophosphorus
acid is adhered to the intermediate organometallic layer.
30. The fluidic channel of claim 29 in which the organometallic
layer is a polymeric metal oxide having unreacted alkoxide and/or
hydroxyl groups.
31. The fluidic channel of claim 19, which is a polymeric
material.
32. The fluidic channel of claim 29 in which the self-assembled
monolayer is chemically bonded to the organometallic layer.
33. The fluidic channel of claim 19 in which the organophosphorus
acid is an organophosphonic acid.
34. The fluidic channel of claim 19 in which the organophosphorus
acid is an organophosphonic acid or derivative thereof comprising a
compound or a mixture of compounds of the structure: ##STR00009##
wherein x is 0 to 1, y is 1, z is 1 to 2 and x+y+z=3; R and R'' are
each independently a hydrocarbon or substituted hydrocarbon radical
having a total of 1 to 30 carbon atoms or an oligomeric group, R'
is H, a metal or lower alkyl.
35. The fluidic channel of claim 34 where R and R'' are each
independently a fluorine-substituted hydrocarbon radical.
36. The fluidic channel of claim 34 in which R and/or R'' is a
group of the structure: ##STR00010## where A is an oxygen radical
or a chemical bond; n is 1 to 6; Y is F or C.sub.nF.sub.2n+1; b is
2 to 20, m is 0 to 6 and p is 0 to 18.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority from U.S.
Provisional Patent Application Ser. No. 61/574,935, filed Aug. 11,
2011.
FIELD OF THE INVENTION
[0002] The present invention relates to the treatment of fluidic
channels such as those in a closed system where a fluid such as a
liquid or a gas is circulated for cooling purposes, or an open
system where the channel is connected at one end to a material
source and at the other end to an opening such as a nozzle for
distributing the material. More particularly, this invention
relates to treating the interior walls of a fluidic channel with a
substance that repels the fluid from the interior walls thereby
preventing interaction between the fluid and the interior
walls.
BACKGROUND OF THE INVENTION
[0003] Controlling the movement of fluids through channels is
important in a number of technologies. Often surface effects of the
channel adversely affect the fluid flow. Metals such as steel and
aluminum are common industrial fluidic channel materials and can
have unbound electrons; exposed polar molecules that can generate a
surface charge and become reactive with the fluid. This reactivity
can impede flow and even form a deposit within the channel further
impeding flow. Also, in the case of an open system, such reactivity
can result in unwanted materials passing through the open end of
the channel.
[0004] To overcome this problem, the channel material can be
selected from an inert material such as a noble metal that is
prohibitively expensive, or an inert polymeric material that may
not be suitable for high temperature applications.
[0005] Coating the interior walls of the channel with a coating
that would repel the fluids may not be satisfactory, particularly
with microchannels, because the thickness of the conventional
coatings may itself impede flow.
SUMMARY OF THE INVENTION
[0006] The present invention is a method of depositing a thin
coating of nano dimensions within a fluidic channel comprising:
[0007] (a) contacting the interior walls of the fluidic channel
either directly or indirectly through an organometallic coating
with a solution of an organophosphorus acid in a diluents,
[0008] (b) removing the diluent, and
[0009] (c) forming a self-assembled monolayer of the
organophosphorus acid on the interior walls of the fluidic
channel.
[0010] By being of nano dimensions, the self-assembled monolayers
do not substantially physically impede fluid flow. Also, the organo
groups of the self-assembled monolayer are selected so as to repel
the fluid, for example, if the fluid is a polar substance such as a
water glycol mixture used as a coolant in radiators, the organo
groups can be long chain hydrocarbons and/or fluoro-substituted
hydrocarbons that make the self-assembled monolayer
hydrophobic.
DETAILED DESCRIPTION
[0011] For purposes of the following detailed description, it is to
be understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than where otherwise indicated, all
numbers expressing, for example, quantities of ingredients used in
the specification and claims are to be understood as being modified
in all instances by the term "about". Accordingly, unless indicated
to the contrary, the numerical parameters set forth in the
following specification and attached claims are approximations that
may vary depending upon the desired properties to be obtained by
the present invention. At the very least, and not as an attempt to
limit the application of the doctrine of equivalents to the scope
of the claims, each numerical parameter should at least be
construed in light of the number of reported significant digits and
by applying ordinary rounding techniques. Notwithstanding that the
numerical ranges and parameters setting forth the broad scope of
the invention are approximations, the numerical values are reported
as precisely as possible. Any numerical value, however, inherently
contains certain errors necessarily resulting from the standard
variation found in their respective testing measurements.
[0012] Also, it should be understood that any numerical range
recited herein is intended to include all sub-ranges subsumed
therein. For example, a range of "1 to 10" is intended to include
all sub-ranges between (and including) the recited minimum value of
1 and the recited maximum value of 10, that is, having a minimum
value equal to or greater than 1 and a maximum value of equal to or
less than 10.
[0013] In this application, the use of the singular includes the
plural and plural encompasses singular, unless specifically stated
otherwise. In addition, in this application, the use of "or" means
"and/or" unless specifically stated otherwise, even though "and/or"
may be explicitly used in certain instances.
[0014] The term "polymer" is also meant to include copolymer and
oligomer.
[0015] The term "acid" is meant to include substances that donate a
proton in a chemical reaction to a base. The term acid also
includes "acid derivative" that is a material that behaves
similarly to an acid such as acid salts, and acid esters,
particularly lower alkyl esters containing from 1 to 4 carbon
atoms.
[0016] The expression "self-assembled monolayer adhered to the
interior walls of the fluidic channel or to the intermediate
organometallic coating" means that adherence may be through
physical attraction or through chemically bonding. With physical
attraction it is believed the organophosphorus acid is in the form
of the acid. In the case of chemical bonding it is believed the
acid forms an ionic or covalent bond with reactive groups on the
interior walls of the fluidic channel or the organometallic
coating.
[0017] The term "solutions" is meant to include homogeneous
mixtures of one substance in another. Liquid solutions are
optically clear because the particle size of the dissolved material
is less than the wavelength of visible light. The term solution
also includes "dispersions" that are non-homogeneous mixtures of
one substance in another. Liquid dispersions are translucent and
also include emulsions that are optically opaque because the
particle size of the dispersed particle is greater than the
wavelength of visible light. The dispersed material itself may be
of such particle size or it may associate with itself or the
dispersing medium forming micelles.
[0018] The term "diluent" is meant to include a solvent and a
dispersant.
[0019] The term "metal" is meant to include metals, metal
compounds, metal alloys and metalloids.
[0020] The term "fluidic channel" or "fluid channel" means a
conduit, usually enclosed and of circular, oval or rectangular
configuration through which a fluid such as a liquid or gas is
passed. The fluidic channel may be associated with a closed circuit
in which the fluid circulates through a loop in a substantially
continuous manner such as a loop associated with a radiator, or an
open circuit in which the fluid flows from a source to an open end
or nozzle end such as a fluidic channel associated with a
dispensing device or means such as the printing head of an inkjet
printer. Other examples of fluidic channels are stencils, needles
and microchannels that are micro-dimension fluidic channels such as
those associated with DNA chips (microarrays).
[0021] The fluidic channel may be made from metal or a polymer.
Examples of metals are tantalum, aluminum, copper, titanium, and
iron and alloys of such metals, such as steel, including stainless
steel, and brass. The invention is particularly useful with
materials that contain surface hydroxyl or oxide groups such as
native oxide layers associated with many metals and their alloys.
The invention is also useful with polymeric materials that have
reactive functional groups. Examples are polymers that contain
hydroxyl groups such as acrylic polymers made from one or more
monomers containing hydroxyl groups.
[0022] The organophosphorus acid may be an organophosphoric acid,
an organophosphonic acid or an organophosphinic acid. The organo
groups may be monomeric or polymeric.
[0023] Examples of monomeric phosphoric acids are compounds or
mixtures of compounds having the following structure:
(RO)--P(O)--(OR').sub.y
wherein x is 1-2, y is 1-2 and x+y=3, R preferably is a radical
having a total of 1-30, preferably 6-18 carbons, where R' is H, a
metal such as an alkali metal, for example, sodium or potassium or
lower alkyl having 1 to 4 carbons, such as methyl or ethyl.
Preferably, a portion of R' is H. The organic component of the
phosphoric acid (R) can be aliphatic (e.g., alkyl having 2-20,
preferably 6-18 carbon atoms) including an unsaturated carbon chain
(e.g., an olefin), or can be aryl or aryl-substituted moiety. At
least one of the organo groups can contain terminal or omega
functional groups as described below.
[0024] Examples of monomeric phosphonic acids are compounds or
mixtures of compounds having the formula:
##STR00001##
wherein x is 0-1, y is 1, z is 1-2 and x+y+z is 3. R and R''
preferably are each independently a radical having a total of 1-30,
preferably 6-18 carbons. R' is H, a metal, such as an alkali metal,
for example, sodium or potassium or lower alkyl having 1-4 carbons
such as methyl or ethyl. Preferably at least a portion of R' is H.
The organic component of the phosphonic acid (R and R'') can be
aliphatic (e.g., alkyl having 2-20, preferably 6-18 carbon atoms)
including an unsaturated carbon chain (e.g., an olefin), or can be
an aryl or aryl-substituted moiety. At least one of the organo
groups can contain terminal or omega functional groups as described
below.
[0025] Examples of monomeric phosphinic acids are compounds or
mixtures of compounds having the formula:
##STR00002##
wherein x is 0-2, y is 0-2, z is 1 and x+y+z is 3. R and R''
preferably are each independently radicals having a total of 1-30,
preferably 6-18 carbons. R' is H, a metal, such as an alkali metal,
for example, sodium or potassium or lower alkyl having 1-4 carbons,
such as methyl or ethyl. Preferably a portion of R' is H. The
organic component of the phosphinic acid (R, R'') can be aliphatic
(e.g., alkyl having 2-20, preferably 6-18 carbon atoms) including
an unsaturated carbon chain (e.g., an olefin), or can be an aryl or
aryl-substituted moiety. Examples of organo groups which may
comprise R and R'' include long and short chain aliphatic
hydrocarbons, aromatic hydrocarbons and substituted aliphatic
hydrocarbons and substituted aromatic hydrocarbons. Examples of
substituents include fluoro and perfluoro such as
CF.sub.3(C.sub.nF.sub.2n)CH.sub.2CH.sub.2PO.sub.3H.sub.2. At least
one of the organo groups can contain terminal or omega functional
groups as described below. Examples of terminal or omega functional
groups include carboxyl such as carboxylic acid, hydroxyl, amino,
imino, amido, thio and phosphonic acid.
[0026] Representative of the organophosphorus acids are as follows:
amino trismethylene phosphonic acid, aminobenzylphosphonic acid,
3-amino propyl phosphonic acid, O-aminophenyl phosphonic acid,
4-methoxyphenyl phosphonic acid, aminophenylphosphonic acid,
aminophosphonobutyric acid, aminopropylphosphonic acid,
benzhydrylphosphonic acid, benzylphosphonic acid, butylphosphonic
acid, carboxyethylphosphonic acid, diphenylphosphinic acid,
dodecylphosphonic acid, ethylidenediphosphonic acid,
heptadecylphosphonic acid, methylbenzylphosphonic acid,
naphthylmethylphosphonic acid, octadecylphosphonic acid,
octylphosphonic acid, pentylphosphonic acid, phenylphosphinic acid,
phenylphosphonic acid, bis-(perfluoroheptyl) phosphinic acid,
perfluorohexyl phosphonic acid, styrene phosphonic acid, dodecyl
bis-1,12-phosphonic acid.
[0027] In addition to the monomeric organophosphorus acids,
oligomeric or polymeric organophosphorus acids resulting from
self-condensation of the respective monomeric acids may be used. A
preferred oligiomeric group is where R and/or R'' is a group of the
structure:
##STR00003##
where A is an oxygen radical or a chemical bond; n is 1 to 20; Y is
H, F, C.sub.nH.sub.2n+1 or C.sub.nF.sub.2n+1; X is H or F; b is at
least 1,m is 0 to 50, and p is 1 to 20.
[0028] The organophosphorus acid is typically dissolved or
dispersed in a diluent to form a solution. Suitable diluents
include alcohols such as methanol, ethanol or propanol; aliphatic
hydrocarbons such as hexane, isooctane and decane, ethers, for
example, tetrahydrofuran and dialkylethers such as diethylether.
Diluents for fluorinated materials can include perfluorinated
compounds such as perfluorinated tetrahydrofuran. Also, aqueous
alkaline solutions such as sodium and potassium hydroxide can be
used as the diluent.
[0029] Adjuvant materials may be present in the solution. Examples
include surface active agents, stabilizers, wetting agents and
anti-static agents. The adjuvants if present are present in amounts
of up to 30 percent by weight based on the non-volatile content of
the organic acid composition.
[0030] The concentration of the organophosphorus acid in the
solution is not particularly critical but is at least 0.01
millimolar, typically 0.01 to 100 millimolar, and more typically
0.1 to 50 millimolar. The solution can be prepared by mixing all of
the components at the same time or by adding the components in
several steps.
[0031] The organophosphorus acid solution can be contacted with the
interior walls of the fluidic channel typically by pumping the
solution through the channel, removing the organophosphorus acid
from the channel and evaporating the solvent at ambient
temperatures or by the application of heat.
[0032] The resultant layer typically is of nano dimensions, having
a thickness of no greater than 100, typically about 10-100
nanometers or less. The layer may be hydrophobic, having a water
contact angle greater than 70.degree., typically from
75-130.degree.. The water contact angle can be determined using a
contact angle goniometer such as a TANTEC contact angle meter Model
CAM-MICRO.
[0033] As mentioned above, the organophosphorus acid can be applied
directly to the fluidic channel or can be applied indirectly to the
fluidic channel through an intermediate organometallic coating.
When better adhesion and durability is desired, an organometallic
coating should be applied to the metal substrate followed by
application of the organophosphorus acid.
[0034] The organometallic compound is preferably derived from a
metal or metalloid, preferably a transition metal, selected from
Group III and Groups IIIB, IVB, VB and VIB of the Periodic Table.
Transition metals are preferred, such as those selected from Groups
IIIB, IVB, VB and VIB of the Periodic Table. Examples are tantalum,
titanium, zirconium, lanthanum, hafnium and tungsten. Niobium is
also a suitable metal. The organo portion of the organometallic
compound is selected from those groups that are reactive with the
organophosphorus acid. Also, as will be described later, the organo
group of the organometallic compound is believed to be reactive
with groups on the surfaces being treated such as oxide and
hydroxyl groups. Examples of suitable organo groups of the
organometallic compound are alkoxide groups containing from 1 to
18, preferably 2 to 4 carbon atoms, such as ethoxide, propoxide,
isopropoxide, butoxide, isobutoxide, tert-butoxide and
ethylhexyloxide. Mixed groups such as alkoxide, acetyl acetonate
and chloride groups can be used.
[0035] The organometallic compounds can be in the form of simple
alkoxylates or polymeric forms of the alkoxylate, and various
chelates and complexes. For example, in the case of titanium and
zirconium, the organometallic compound can include:
a. alkoxylates of titanium and zirconium having the general formula
M(OR).sub.4, wherein M is selected from Ti and Zr and R is
C.sub.1-18 alkyl, b. polymeric alkyl titanates and zirconates
obtainable by condensation of the alkoxylates of (a), i.e.,
partially hydrolyzed alkoxylates of the general formula
RO[--M(OR).sub.2O--].sub.x-1R, wherein M and R are as above and x
is a positive integer, c. titanium chelates, derived from ortho
titanic acid and polyfunctional alcohols containing one or more
additional hydroxyl, halo, keto, carboxyl or amino groups capable
of donating electrons to titanium. Examples of these chelates are
those having the general formula
Ti(O).sub.a(OH).sub.b(OR').sub.c(XY).sub.d
wherein a=4-b-c-d; b=4-a-c-d; c=4-a-b-d; d=4-a-b-c; R' is H, R as
above or X-Y, wherein X is an electron donating group such as
oxygen or nitrogen and Y is an aliphatic radical having a two or
three carbon atom chain such as
[0036] i. --CH.sub.2CH.sub.2--, e.g., of ethanolamine,
diethanolamine and triethanolamine,
##STR00004##
[0037] ii. e.g., of lactic acid,
##STR00005##
[0038] iii. e.g., of acetylacetone enol form, and
##STR00006##
[0039] iv. e.g., as in 1,3-octyleneglycol,
d. titanium acrylates having the general formula
Ti(OCOR).sub.4-n(OR).sub.n wherein R is C.sub.1-18alkyl as above
and n is an integer of from 1 to 3, and polymeric forms thereof, e.
mixtures thereof.
[0040] The organometallic compound can be dissolved or dispersed in
a diluent to form a solution. Examples of suitable diluents are
alcohols such as methanol, ethanol and propanol, aliphatic
hydrocarbons, such as hexane, isooctane and decane, ethers, for
example, tetrahydrofuran and dialkyl ethers such as diethyl ether.
Alternatively, the organometallic compound can be used neat and
applied by vapor deposition techniques.
[0041] Also, adjuvant materials may be present in the solution.
Examples include stabilizers such as sterically hindered alcohols,
surfactants and anti-static agents. The adjuvants if present are
present in amounts of up to 30 percent by weight based on the
non-volatile content of the composition.
[0042] The concentration of the organometallic compound in the
composition is not particularly critical but is usually at least
0.01 millimolar, typically from 0.01 to 100 millimolar, and more
typically from 0.1 to 50 millimolar.
[0043] The organometallic treating composition can be obtained by
mixing all of the components at the same time or by combining the
ingredients in several steps. If the organometallic compound chosen
is reactive with moisture, (e.g. in the case of titanium (IV)
n-butoxide, tantalum (V) ethoxide, aluminum (III) isopropoxide
etc,) care should be taken that moisture is not introduced with the
diluent or adjuvant materials and that mixing is conducted in a
substantially anhydrous atmosphere.
[0044] The organometallic solution can be applied to the fluidic
channel surface by pumping the solution through the channel. The
solution removed from the channel and the diluent evaporated. This
can be accomplished by heating to 50-200.degree. C. or by simple
exposure to ambient temperature, that is, from 20-25.degree. C.
Alternately, the organometallic compound can be vaporized and the
vapor passed through the fluidic channel. The resulting film may in
the form of a polymeric metal oxide with unreacted alkoxide and
hydroxyl groups. This is accomplished by depositing the film under
conditions resulting in hydrolysis and self-condensation of the
alkoxide. These reactions result in a polymeric coating being
formed. The conditions necessary for these reactions to occur is to
deposit the film in the presence of water, such as a
moisture-containing atmosphere, however, these reactions can be
performed in solution by the careful addition of water. The
resulting film has some unreacted alkoxide groups and/or hydroxyl
groups for subsequent reaction and possible covalent bonding with
the organophosphorus acid. Although not intending to be bound by
any theory, it is believed the polymeric metal oxide is of the
structure:
[M(O).sub.x(OH).sub.y(OR).sub.z].sub.n
where M is the metal of the invention, R is an alkyl group
containing from 1 to 30 carbon atoms; x+y+z=V, the valence of M; x
is at least 1, y is at least 1, z is at least 1; x=V-y-z; y=V-x-z;
z=V-x-y; n is greater than 2, such as 2 to 1000.
[0045] When the organometallic compound is used neat and applied by
chemical vapor deposition techniques in the absence of moisture, a
thin metal alkoxide film is believed to form. Polymerization, if
any occurs, is minimized and the film may be in monolayer
configuration. The resulting film typically has a thickness of 0.5
to 100 nanometers. When the organometallic compound is subjected to
hydrolysis and self-condensation conditions as mentioned above,
somewhat thicker films are formed.
[0046] Although not intending to be bound by any theory, it is
believed the acid groups of the organophosphorus acid chemically
bond with the oxide or hydroxyl groups on the surface of the
substrate being treated or chemically bond with the hydroxyl or
alkoxide group of the organometallic coating, resulting in a
durable film. It is believed that the organophosphorus acid forms a
self-assembled monolayer on the surface of the substrate.
Self-assembled layers or films are formed by the adsorption and
spontaneous organization of the material on the surface of the
substrate. The organophosphorus acids useful in the practice of the
invention are amphiphilic molecules that have two functional
groups. The first functional group, i.e., the head functional
group, is the polar phosphorus acid group and attaches by physical
attraction or by chemical bonding to the surface of the substrate.
The second functional group, the organophosphorus acid group, i.e.,
the tail, extends outwardly from the surface of the substrate. If
the omega or terminal portion of the tail contains a functional
group such as those mentioned above, the organophosphorus layer can
serve as an anchor or primer for a subsequently applied coating
with coreactive functional groups. As an example, the
organophosphorus acid can contain terminal amino and/or carboxylic
acid groups and the subsequently applied layer can be an epoxy
containing resin or polymer. The amino and/or carboxylic acid
groups are reactive with the epoxy groups resulting in a multilayer
coating with good adhesion between the organophosphorus layer and
the subsequently applied layer obtained from the epoxy resin or
polymer.
[0047] The invention is now set forth in the following claims.
* * * * *