ZA200109237B

ZA200109237B - Method for improving heat efficiency using silane coatings and coated articles produced thereby.

Info

Publication number: ZA200109237B
Application number: ZA200109237A
Authority: ZA
Inventors: John B Schutt; Jeffrey Stanich; Anthony A Gedeon
Original assignee: Adsil Lc
Priority date: 2000-02-08
Filing date: 2001-11-08
Publication date: 2003-08-22

Description

METHOD FOR IMPROVING HEAT EFFICIENCY USING SILANE COATINGS

AND COATED ARTICLES PRODUCED THEREBY

Cross-Reference to Related Applications

This application claims priority from Provisional Applications Nos. 60/181,061, 60/185,354, 60/185,367, and 60/236,158, filed February 8, 2000, . February 28, 2000, February 28, 2000, and September 29, 2000, respectively.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to use of silane based coating compositions for coating heat exchange systems, such as HVAC systems, whereby heating efficiencies and corrosion protection are both substantially improved. More particularly, the present invention is concerned with improving performance and useful lifetime of heat exchange systems wherein the heat exchange surfaces are coated with a very thin coating of glass-like silane based coating composition which penetrate into very small spaces at the interface between and in the heat exchange surfaces to provide a parallel © path for heat transfer and prevent corrosion, thereby greatly improving short- and oo long-term efficiency.

Discussion of the Prior Art

Silane, silanol and siloxane compounds have been used for many years, as both solvent-based and aqueous-based, formulations, with or without modification with organic substituents, for such applications as coupling agents for glass or other inorganic substrates to organic compounds; non-permanent (limited life) water repellants for concrete and woven fabric materials; synthetic rubber like compounds for adhesives and sealers; adhesion modifiers for organic paints and inorganic coatings; and other property enhancing uses which take advantage of having the ability to form moderate to strong hydrogen bonds to organic and inorganic surfaces, more tenaciously than most classes of polymeric coatings.

U.S. Patents No. 3,944,702, 3,976,497, 3,986,997 and 4,027,073 describe coating compositions which are acid dispersions of colloidal silica and hydroxylated silsequioxane in an alcohol-water medium.

U.S. 4,113,665 discloses chemically resistant ambient curable coatings based on a binder of which the major portion is prepared by reacting, in an acidic solution, trialkoxysilanes (e.g., methyltriethoxysilane) with aliphatic polyols, silicones or both.

: L wo 01/58972 PCT/US01/40052

ST YI

Barium fillers, such as barium metaborate, may be added to provide resistance to sulfur dioxide. Zinc oxide or metallic zinc may be included for further corrosion resistance. The compositions may be applied to, e.g., steel petroleum tanks, by spraying, concrete, vitreous surfaces.

U.S. 4,413,086 describes water reducible coating compositions containing organosilane-polyol which is a reaction product between certain hydrophilic organic polycarbinols and organosilicon material, e.g., organosilane, curing agent (e.g., aminoplast resin), organic solvent (optional), essentially unreacted polyol (optional), essentially unreacted hydrolyzed and condensed organosilane (optional), water (optional) and pigment (optional).

U.S. 4,648,904 describes an aqueous emulsion of (a) hydrolyzable silane, inclusive of methyltrimethoxysilane, (b) surfactant (e.g., Table I, col. 4) and (c) water.

The coatings may be used for rendering masonry water repellant.

U.S. 5,275,645 is purported to provide an improvement to the acid-catalyzed organosilane coating compositions of the above-mentioned U.S. 4,113,665.

According to this patent a protective coating is obtained at ambient temperature from.

T7777 acoating composition containing organosilanes having an Si-O bond, using an amine catalyst and an organometallic catalyst.

U.S. 5,879,437 describes a coating composition containing a tetraalkyl silicate or monomeric or oligomeric hydrolysis product thereof, present in a proportion of 40- 90% by weight based on the non-volatile content of the composition and a hydrous oxide sol (Type A or Type B), in an amount such that the oxide constitutes 10-60 % by weight of the non-volatiles. According to the patentees, this coating composition is suitable for the pretreatment of solid surfaces such as metals generally, including steel, titanium, copper, zinc and, particularly aluminum, to improve adhesion properties of the pretreated surface to subsequently applied coatings, such as paint, varnish, lacquer; or of adhesive, either in the presence or absence of a lubricant.

U.S. 5,882,543 describes methods and compositions for dehydrating, passivating and coating HVAC (heating, ventilating and air conditioning) systems.

The compositions include an organometalloid and/or organometallic compound, which reacts with water in the system. The sealing function of these compositions is apparently obtained by introducing the composition to the fluid enclosure and upon exiting from an opening, the composition (i.e., organometallic) reacts with atmospheric moisture to seal the opening.

U.S. 5,954,869 discloses an antimicrobial coating from water-stabilized organosilanes obtained by mixing an organosilane having one or more hydrolyzable groups, with a polyol containing at least two hydroxyl groups. This patent includes a broad disclosure of potential applications and end uses, e.g., column 4, lines 35-53; columns 23-25.

U.S. 5,959,014 relates to organosilane coatings purported to have extended shelf life. Organosilane of formula R,SiX4., (n=0-3;R = non-hydrolyzable group; X = hydrolyzable group) is reacted with a polyol containing at least three hydroxyl groups, wherein at least any two of the at least three hydroxyl groups are separated by at least three intervening atoms.

U.S. 5,929,159, to J. Schutt and A. Gedeon, and commonly assigned with the present application, describes an oligomeric coating composition in the form of an aqueous composition comprising a dispersion of divalent metal cations (especially,

Ca, Mn, Cu and Zn divalent ions) in lower aliphatic alcohol-water solution of the partial condensate of at least one silanol (at least about 70 wt.% of which was methyltrimethoxy silane), and acid, in amount to provide a pH in the range of from about 2.5 to about 6.2, the amount of the divalent metal cations being from about 1.2 to about 2.4 millimoles, per molar equivalent of the partial condensate, calculated as methyl silane sesquioxide. It is also described to provide a coating composition as a two part formulation, the first part being an acidic aqueous dispersion of divalent metal cation, having a pH of from about 2.2 to about 2.8; and the second part a non- aqueous composition comprising at least one trialkoxy silane; with at least one of the first and second parts comprising a volatile organic solvent. The corrosion resistant coatings may be provided as aqueous-alcoholic dispersions of the partial condensate of monomethyl silanol (obtained by hydrolysis of monomethyl alkoxysilane) alone or in admixture with minor amounts of other silanol, e.g., phenyltrimethoxysilanol, gamma-glycidyloxy silanol, and the like, wherein the reaction is catalyzed by divalent metal ions, e.g., Ca*?, typically from alkaline earth metal oxides. When these coating are applied to, e.g., boat hulls, such as aluminum hulls, they are highly effective in preventing corrosion from salt water for extended periods.

Thus, this patent indicates that the patented coating compositions are suitable for application to various types of substrates, but especially, marine surfaces, such as aluminum boat hulls, to render the surface corrosion resistant in a salt water environment. Other representative potential applications and substrates for the

A 5, WO 01/58972 PCT/US01/40052

OR patented silane based coating compositions mentioned in the Schutt and Gedeon patent include coatings for concrete/rock, wherein the coating can penetrate the porous materials, due to its low viscosity and active nature; metals/plastics, wherein the coating is preferably applied to very clean surfaces but will itself clean the pores in the metal or plastic and exhume the contamination which generally rises to the surface of the coating.

The compositions of the Schutt, et al patent are oligomeric coatings using a variety of siloxane bond forming monomers as described. Subsequent modifications of the compositions of the U.S. 5,929,159 patent have been developed by John Schutt and are described, for example, in copending provisional applications Serial Nos. 60/185,367 and 60/185,354, both filed on February 28, 2000, and Serial No. 60/236,158, filed September 25, 2000. Basically, these provisional applications disclose formulations for silane/siloxane/silanol oligomeric compositions, both solvent (non-aqueous) and water (aqueous) based, which effectively bond to many different metallic and non-metallic surfaces by means of siloxy (-Si-O-) bonds.

The compositions disclosed by the 5,929,159 patent and provisional Co ~~ ~~ —— — applications can cure under ambient conditions and are catalyzed ading, For example, acid, alkali. and metal alkoxide, catalysts. They may contain organic additives forming hydrogen bonds of greater energy than those formed with water. Protection of metallic surfaces occur because bonds of greater covalency are created which are more robust than dipole or dispersion forces.

SUMMARY OF THE INVENTION

It has now been discovered that the coating compositions of US 5,929,159, and subsequently developed formulations, as described in the aforementioned three provisional applications, SN 60/185,354, 60/185,367, and 60/236,158, the entire disclosures of which are incorporated herein, in their entireties, by reference thereto, are very highly effective in providing strongly adherent, corrosion resistant coatings for heat exchange systems, including, especially, air conditioning units and other

HVAC systems, and the individual components thereof. Although not wishing to be bound by any particular theory of operation, it is believed that the effectiveness of these siloxy bond forming coating compositions arises, at least in part, from the oligomeric nature of these compositions. The low molecular weight of the oligomeric components and the low viscosity of the composition, enables them to penetrate the defect surface structure found in all surfaces, with the option of creating dendritic-like

YS networks over a surface. In particular, scanning electron microphotographs show that compositions as described herein penetrate defects having nanometer dimensions while forming films on the order of millionths of an inch in depth.

These compositions may be applied not only to coat new heat exchange systems and component parts thereof, e.g., coils, condensers and the like, but also may be applied in situ to existing heat exchange systems and component parts, even when the system or individual parts thereof are corroded.

Accordingly, the present invention provides a method for improving heat exchange (thermal) efficiency of heat transfer surfaces and corrosion protection for heat transfer surfaces and heat transfer systems and component parts thereof by coating the heat transfer surfaces alone or the entire heat transfer system or component parts thereof , with a low viscosity, penetrating, reactive, curable, film- forming, silane-based, coating composition and curing the composition to thereby form an at least substantially continuous glass-like coating on the coated surface, the coating extending into voids and defects which may be present in the surface, whereby a thermally conductive corrosion protective layer is provided on the heat transfer surface, and any other coated surfaces.

In one embodiment, the present invention provides a method for improving - efficiency of heat transfer from a heat transfer medium flowing in heat transfer contact with a heat transfer surface of a thermally conductive component of a heat transfer system across the heat transfer surface.

In a particularly preferred embodiment of the invention, the coating composition is applied to at least the heat exchange surfaces of a fin and tube heat exchange system.

In the preferred embodiment of the invention, the coating composition is an aqueous or non-aqueous oligomeric silane coating composition formed by admixing (a) at least one silane of the formula (1)

R'uSi(OR)4.q (1 where R' represents a lower alkyl group, a C4-Cg aryl or a functional group including at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional groups; (b) silane condensation catalyst, and (c) lower alkanol solvent, and optionally, one or more of (d) colloidal aluminum hydroxide; (e) metal alcoholate of formula (2):

SEF UT

M(ORY),, (2) where M is a metal of valence 2, 3 or 4, or mixture of two or more such metals;

R represents a lower alky! group; and, m represents a number or 2, 3 or 4; (f) a silica component selected from the group consisting of alkali metal silicate, ethyl orthosilicate, ethyl polysilicate, and colloidal silica dispersed in lower alkanol; (g) color forming silanol condensation catalyst; (h) epoxysilane; and, (i) ultrafine titanium dioxide ultraviolet light absorber.

The coating composition is applied to at least a portion of a heat transfer surface and the applied coating composition is allowed to cure to form a highly corrosion resistant and strongly adherent coating. This coating is effective to fill micropores and crevices in the heat transfer surface to effectively increase the area

I5 available for heat transfer.

Similarly, the present invention provides a method for increasing the contact LL === “area between first and second heat transfer surfaces in thermal contact with each other, thereby improving the heat transfer efficiency across the thermally contacting heat transfer surfaces. The method according to this embodiment comprises applying to the thermally contacting heat transfer surface of at least one of the first and second heat transfer surfaces, a low viscosity, penetrating, curable, reactive, film-forming, coating composition and curing the composition to thereby form an at least substantially continuous glass-like coating on the heat transfer surface, the coating extending into voids and defects which may be present in said heat transfer surface, whereby a thermally conductive corrosion protective layer is provided on the heat transfer surface.

Here again, the preferred coating composition is an aqueous or non-aqueous oligomeric silane coating composition formed by admixing (a) at least one silane of the formula (1)

R'.Si(OR)4-n (1) where R' represents a lower alkyl group, a C4-C; aryl or a functional group including at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional groups; (b) silane condensation catalyst, and (c) lower alkanol solvent, and optionally, one or more of

’ mt : (d) colloidal aluminum hydroxide; (e) metal alcoholate of formula (2): )

M(OR’), 2) where M is a metal of valence 2, 3 or 4, or mixture of two or more such metals; : 5 R represents a lower alkyl group; and, m represents a number or 2, 3 or 4; (f) a silica component selected from the group consisting of alkali metal : silicate, ethyl orthosilicate, ethyl polysilicate, and colloidal silica dispersed in lower alkanol; (g) color forming silanol condensation catalyst; (h) epoxysilane; (i) ultrafine titanium dioxide ultraviolet light absorber: (j) water; and (k) co-solvent.

In a particularly preferred embodiment, the efficiency of heat exchange apparatus of the type wherein a metal-to-metal contact is present wherein a metal heat transfer surface is swaged or force fit to a metal heat transfer fluid conveyance is improved by applying to the metal to metal contact a low viscosity, penetrating, curable, reactive, film-forming, coating composition and curing the composition to thereby form an at least substantially continuous glass-like coating on said heat transfer surface, said coating extending into voids and defects which may be present in said heat transfer surface, whereby a thermally conductive corrosion protective layer is provided on said heat transfer surface. Preferably. the above described aqueous or non-aqueous oligomeric silane coating composition containing the silane of formula (1), silane condensation catalyst and solvent, and one or more optional ingredients, is applied to the interface of the metal-to-metal contact portions, whereby the oligomeric coating composition will displace gasses and liquids in the interface; and allowing the coating composition to cure to a film thickness of from about 5 to about 150 millionths of an inch, while also filling microvacancies in the metal surfaces at the metal-to-metal contact interface.

The present invention also provides the coated heat exchange surfaces and heat exchange systems and component parts, especially, fin and tube heat exchange systems.

: ¢ WG 01/58972 PCT/US01/40052 « DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED

EMBODIMENTS

The coating compositions used in the present invention may generally be characterized as low molecular weight oligomeric silane based coatings. As used in this context the term “silane” is intended to include not only silanes but also silanols and siloxanes and the low molecular weight partial condensation products thereof.

The term “low molecular weight” is intended to refer to the general absence of large or bulky organic molecules or moieties as part of the silane components, namely, wherein the organic substituents are generally limited to lower alkyl groups, especially alkyl groups containing from 1 to 4 carbon atoms, especially, 1 to 3 carbon atoms, including, in particular, methyl, ethyl, n-propyl and iso-propyl groups, and aryl groups of no more than about 8 carbon atoms, especially, no more than about 6 carbon atoms, such as, for example, phenyl, benzyl, and phenethyl.

Still further, the coating compositions of this invention are characterized by low viscosity to facilitate the penetration into the microcrevices and microvoids present on the heat transfer surface. As used herein, “low viscosity” is taken to mean + meee = ~~ ~ the ability to penetrate into micron and submicron size voids in metal surfaces.

Typically, the coating compositions of the present invention are characterized by a coating viscosity, measured using a No. 2 (#2) Zahn Cup, of from about 4 to about 10 seconds, especially, from about 5 to about 8 seconds, measured at room temperature (approximately 18°C).

The present invention also provides improved heat transfer systems coated with the subject silane based anticorrosion coating compositions as described herein.

In particular, the invention coating compositions may be applied as protective coatings for new or refurbished heat transfer systems and components as well as applied in situ to used, corroded or rusted heat transfer systems and component parts thereof to significantly improve performance and increase the useful life of the treated systems and component parts.

The compositions according to this invention are able to readily penetrate into extremely small spaces and crevices, including down to nanometer inclusions in the indices of the metal substrates used to manufacture heat exchange systems and component parts. As compared to conventional organic coatings, including known silane based coating compositions, the compositions of the present invention are characterized by low cohesive forces and, as a result, tend to wick into such small micro-spaces due to their active chemical nature. Thus, for example, organic coatings, including acrylics, polyurethanes, epoxies and phenolics, will not naturally wick into the small (e.g., micro-voids) metal contact irregularities, even when applied by E-coating (electrocoating) techniques. While it has been suggested in the art to - 5 mix some silane/siloxane compounds with acrylics, acrylic urethanes, organic acids wr and epoxides, however, these known formulations are not able to take advantage of = the small active molecules which characterize the present compositions, which are capable of wicking into extremely small voids in and between thermal contact - surfaces.

The coating compositions used in the present invention are capable of filling small nanometer size voids under driving forces of capillary action and Helmoltz free energy, displacing gasses and/or reacting with water or other chemicals. The ability of the coating compositions of this invention to migrate and penetrate capillary structures releasing Helmoltz free energy allows them to displace molecules bonded by means of secondary and tertiary valence forces and provide protection by forming micron range thickness coatings, on the order of from about 5 to about 150 millionths of an inch. These driving forces even allow such penetration to occur under the high pressures, e.g., 2000 p.s.i., present in joints of such heat exchangers. Accordingly, the coating of the present invention are highly effective for increasing the efficiency of heat exchangers by providing parallel thermal paths between metal contact of, for example, heat dispersing fins and tubing or piping carrying fluids or gases for absorption or dispersion of heat.

The preferred low viscosity, penetrating, active coating compositions used in the present invention are silane based coating compositions, and may be may be aqueous or non-aqueous. Preferred coating compositions are formed by admixing (a) at least one silane of formula (1)

R'4Si(OR")smn (1) where R' represents a lower alkyl group, a C¢-Cs aryl group or a functional group including at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional groups; with (b) a silane condensation catalyst, which may be, for example, an acid, a base, or mixed acid-base. The silane(s) and catalyst are contacted in a low viscosity solvent, typically a lower alkanol solvent, such as ethanol, isopropanol, and the like.

One or more additional reactive or functional ingredients may be included in the composition.

: ‘ WG 01/58972 PCT/US01/40052 ne Ce

Representative examples of suitable oligomeric silane coating compositions useful in the present invention have been described in my above-identified patent and co-pending provisional applications and are described briefly below.

I. an aqueous coating composition comprising a dispersion of divalent metal cations in lower aliphatic alcohol-water solution of the partial condensate of at least one silanol of the formula RSi(OH);, wherein R is a radical selected from the group consisting of lower alkyl, or C6-Cs ary! or a functional group including at least one of vinyl, acrylic. amino, mercapto, or vinyl chloride functional groups (e.g., 3.3,3- trifluoropropyl, y-glycidyloxypropyl, and y-methacryloxypropyl), at least about 70 percent by weight of the silanol being CH3Si(OH)3, acid in amount to provide a pH in the range of from about 2.5 to about 6.2, said divalent metal cations being present in an amount of from about 1.2 millimoles to about 2.4 millimoles, per molar equivalent of the partial condensate, calculated as methyl silane sesquioxide;

IL. an aqueous coating composition formed by admixing (A) at least one silane of the formula (1)

R'Si(OR?) (1 ee where eo ST mo

R' is a lower alkyl group, a C¢-Cs aryl group or an N-(2-aminoethyl)-3- aminopropy! group, and

R? is a lower alkyl group; (B) an acid component selected from the group consisting of water-soluble organic acids, H3BO; and H3;POs3; and (D) water;

III. a non-aqueous coating composition formed by admixing (A) at least one silane of formula (1)

R'wSi(OR)4.n 0) wherein R' represents lower alkyl, C¢-Cg aryl, 3,3,3-trifluoropropyl, y- glycidyloxypropyl, y-(meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropyl group;

R? represents lower alkyl group; and n is a number of 1 to 2; and (E) (i) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at least one metal alcoholate of formula (2)

M(OR?),, 0)

IV. a non-aqueous coating composition formed by admixing # 5 (A) at least one silane of formula (1) “re R'.Si(ORY).., (1) wherein R' represents lower alkyl, C4-Csg aryl, 3,3,3-trifluoropropyl, y-

Ea glycidyloxypropyl, y-(meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropy! group;

R? represents lower alkyl or acetyl group; and n is a number of 1 to 2; (B) boric acid, optionally dissolved in lower alkanol; (E) (i) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at = least one metal alcoholate of formula (2)

M(OR?),, (2) wherein M represents a metal of valence m, rR’ represents lower alkyl group m is an number of 2, 3 or 4; and, : (F) silica component selected from the group consisting of ethyl ortho-silicate, ethyl polysilicate and colloidal silica, dispersed in lower alkanol;

V. a non-aqueous coating composition formed by admixing (A) at least one silane of formula (1)

R'»Si(OR?)4.0 M) wherein R' represents lower alkyl, C¢-Cs aryl, 3,3,3-trifluoropropyl, v- (meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropyl group;

R? represents lower alkyl or acetyl group; and nis a number of 1 to 2; (A’) y-glycidyloxypropylitrimethoxysilane; (B) boric acid, optionally dissolved in lower alkanol; (E) (1) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at least one metal alcoholate of formula (2)

M(OR’)r, (2) wherein M represents a metal of valence m,

R® represents lower alkyl group

Il

EE m is an number of 2, 3 or 4;

VI. an aqueous coating composition formed by admixing (A) at least one silane of formula (1) : R':Si(OR)4p (n wherein R' represents lower alkyl, C¢-Cg aryl, or a functional group containing at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and

R? is a lower alkyl group; (B) acid component comprising a member selected from the group consisting of water-soluble organic acids, H;BOj3; and H3POs; and (D) water;

VII. an aqueous coating composition formed by admixing (A) at least one silane of formula (1)

R',Si(OR?). (1) wherein R! represents lower alkyl, Cs-Cs aryl, or a functional group containing at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and

R? is a lower alky! group; fee menses oo =(C)-alkali component; and” Cc TTT TTT TT co (D) water;

VII. an aqueous coating composition formed by admixing (A) at least one silane of the formula (1)

R'Si(OR?), 4) wherein

R' represents lower alkyl group, C¢-Cg aryl group or a bifunctional silane containing vinyl, acrylic, amino, or vinyl chloride functional group; and

R? is a lower alkyl group; (E) (ii) colloidal aluminum hydroxide, (iii) metal alcoholate of the formula (2)

M(OR’)y, 2) wherein

M is a metal of valence m,

R? is a lower alky! group, m is an integer of 3 or 4, or (iii) mixture of (ii) and (iii); and (D) water;

IX. an aqueous coating composition formed by admixing

Claims

TC + WHAT IS CLAIMED IS: 1 Claim 1. A method for improving efficiency of heat transfer from a heat 2 transfer medium flowing in heat transfer contact with a heat transfer surface of a 3 thermally conductive component of a heat transfer system across said heat transfer Ea 4 surface, said method comprising coating at least a portion of said heat transfer surface

5... with a low viscosity, penetrating, curable, reactive, film-forming, coating composition . 6 and curing the composition to thereby form an at least substantially continuous glass- 7 like coating on said heat transfer surface, said coating extending into voids and 8 defects which may be present in said heat transfer surface, whereby a thermally 9 conductive corrosion protective layer is provided on said heat transfer surface. 1 Claim 2. The method of claim 1, wherein said coating composition comprises 2 an aqueous or non-aqueous oligomeric silane coating composition formed by 3 admixing (a) at least one silane of the formula (1) 4 R':Si(OR?)4n M where R' represents a lower alkyl group, a C¢-Cjy aryl group or a functional group 6 including at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional NB J 8 (b) silane condensation catalyst, and 9 (c) lower alkanol solvent, and optionally, one or more of (d) colloidal aluminum hydroxide; 11 (e) metal alcoholate of formula (2): 12 M(OR*)n, 2) 13 where M is a metal of valence 2, 3 or 4, or mixture of two or more such metals; 14 R represents a lower alkyl group; and, m represents a number or 2, 3 or 4; 16 (f) a silica component selected from the group consisting of alkali metal 17 silicate, ethyl orthosilicate, ethyl polysilicate, and colloidal silica dispersed in lower 18 alkanol; 19 (g) color forming silanol condensation catalyst; (h) epoxysilane; 21 (1) ultrafine titanium dioxide ultraviolet light absorber; 22 (j) water; and 23 (k) co-solvent; 24 and curing the applied coating composition.

EN 1 Claim 3. The method of claim 2, wherein said oligomeric silane coating 2 composition comprises (I) an aqueous coating composition comprising a dispersion of 3 divalent metal cations in lower aliphatic alcohol-water solution of the partial 4 condensate of at least one silanol of the formula RSi(OH)s, wherein R is a radical selected from the group consisting of lower alkyl, vinyl, phenyl, 3,3,3-trifluoropropyl, 6 gamma-glycidyloxypropyl, and gamma-methacryloxypropyl, at least about 70 percent 7 by weight of the silanol being CH3Si(OH)3, acid in amount to provide a pH in the 8 range of from about 2.5 to about 6.2, said divalent metal cations being present in an 9 amount of from about 1.2 millimoles to about 2.4 millimoles, per molar equivalent of the partial condensate, calculated as methyl silane sesquioxide. 1 Claim 4. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises (11) 3 (A) at least one silane of the formula (1) 4 R'Si(OR%)3 (M 5 wherein 6 R'is a lower alkyl group, a phenyl group or an LL - ess = 70° NA(2-aminoethyl)-3-aminopropyl group, and 8 R? is a lower alkyl group; 9 (B) acid component selected from the group consisting of water-soluble 10 organic acids, H3BO; and H;PO;; and 1 (D) water. 1 Claim 5. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises, (III) a non-aqueous coating composition formed by admixing 3 (A) at least one silane of formula (1) 4 R'wSi(OR*)son M 5 wherein R' represents lower alkyl, phenyl, 3,3,3-trifluoropropyl, y-glycidyloxypropyl, 6 y-(meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropy! group; 7 R’ represents lower alkyl group; and 8 n is a number of 1 to 2; and 9 (E) (i) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at 10 least one metal alcoholate of formula (2) 11 M(OR’)x 2) 12 wherein M represents a metal of valence m, 13 R? represents lower alkyl group; and

~ om 14 m is a number of 2, 3 or 4. 1 Claim 6. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises, (IV) a non-aqueous coating composition formed by admixing 3 (A) at least one silane of formula (1) 4 R'nSi(OR%s, (1) E 5 wherein R' represents lower alkyl, phenyl, 3,3,3-trifluoropropyl, y-glycidyloxypropyl, 6 y-(meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropy! group; 7 R? represents lower alkyl or acetyl group; and 8 nis a number of 1 to 2; 9 (B) boric acid, optionally dissolved in lower alkanol; 10 (E) (i) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at 11 least one metal alcoholate of formula (2) 12 M(OR%),, (2) 13 wherein M represents a metal of valence m, 14 R® represents [ower alkyl! group 15 m is an number of 2, 3 or 4; and. 16 (F) silica component selected from the group consisting of ethyl ortho-silicate, 17 ethyl polysilicate and colloidal silica, dispersed in lower alkanol. 1 Claim 7. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises, (V) a non-aqueous coating composition formed by admixing 3 (A) at ieast one silane of formula (1) 4 R':Si(OR?)4., ey wherein R! represents lower alkyl, phenyl. 3,3,3-trifluoropropyl, v- 6 (meth)acryloxypropyl, N-(2-aminoethyl)-3-aminopropyl, or aminopropy! group; 7 R? represents lower alkyl or acetyl group; and 8 n is a number of 1 to 2; 9 (A’) y-glycidyloxypropyloxytrimethoxysilane; (B) boric acid, optionally dissolved in lower alkanol: 11 (E) (i) vinyltriacetoxysilane, (ii) colloidal aluminum hydroxide; and/or (iii) at 12 least one metal alcoholate of formula (2) 13 M(OR), (2) 14 wherein M represents a metal of valence m, R’ represents lower alkyl group 16 m is an number of 2, 3 or 4.

(a # A

I Claim 8. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises (V1) an oligomeric silane coating composition formed by 3 admixing 4 (A) at least one silane of formula (1)

s R'wSi(OR)4.n (1 6 wherein R' represents lower alkyl, phenyl, or a functional group containing at least

7 one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and

8 R? is a lower alkyl group;

9 (B) acid component comprising a member selected from the group consisting 10 of water-soluble organic acids, HBO and H3POs; and 11 (D) water.

1 Claim 9. The method of claim 2, wherein the oligomeric silane coating

2 composition comprises, (VII) an aqueous oligomeric silane coating composition

3 formed by admixing

4 (A) at least one silane of formula (1)

R'uSi(OR?)4.n Mm

~~ eo - = -- -6- - wherein R' represents lower-alkyl; phenyl;or a-functional group containing at least RE

7 one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and

8 R? is a lower alkyl group;

9 (C) alkali component; and (D) water.

1 Claim 10. The method of claim 2, wherein the oligomeric silane coating

2 composition comprises (VIII) an aqueous coating composition formed by admixing

3 (A) at least one silane of the formula (1)

4 R'Si(OR?), (1)

5 wherein

6 R' is a lower alkyl group, a phenyl! group or a bifunctional silane containing

7 vinyl, acrylic, amino, or vinyl chloride functional group; and

8 R? is a lower alkyl group;

9 (E) (ii) colloidal aluminum hydroxide, (iii) metal alcoholate of the formula (2) 10 M(OR®),, 0) 11 wherein 12 M is a metal of valence m,

13 R? is a lower alkyl group,

& fo a) 14 m is an integer of 3 or 4, 15 or mixture of (ii) and (iii); and 16 (D) water. 1 Claim 11. The method of claim 2. wherein the oligomeric silane coating R 2 composition comprises (IX) an aqueous coating composition formed by admixing 3 (A) at least one silane of the formula (1) 4 R'Si(OR?); (1 wherein R' is a lower alkyl group, a phenyl group or a bifunctional silane 6 containing vinyl, acrylic, amino, or vinyl chloride functional group; and 7 R? is a lower alkyl group; 8 (D) water; 9 (H) lower alkanol; and (G) chromium acetate hydroxide. 1 Claim 12. The method of claim 2. wherein the oligomeric silane coating 2 composition comprises (X) an aqueous coating composition formed by admixing 3 (A) at least one silane of the formula (1) 4 R'Si(OR?); (1) 5 wherein 6 R' is a lower alkyl group, a phenyl group or a functional group including at 7 least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and 8 R? is a lower alkyl group; 9 (D) water; 10 (F) alkali metal silicate, which may be hydrolyzed; 11 (H) lower alkanol; and 12 (E) (ii) colloidal aluminum hydroxide, (iii) metal alcoholate of the formula (2) 13 M(OR%), 2) 14 wherein M is a metal of valence m, 16 R? is a lower alkyl group, 17 m is an integer of 3 or 4, 18 or mixture of (ii) and (iii). 1 Claim 13. The method of claim 2, wherein the oligomeric silane coating 2 composition comprises, (XI) a non-metallic aqueous coating composition formed by 3 admixing

- WQ 01/58972 PCT/US01/40052 NEP 4 (A) at least one silane of the formula (1) R'Si(OR?); 1) 6 wherein 7 R'is a lower alkyl group, a phenyl group or a functional group including at 8 least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and 9 R? is a lower alkyl group; (A”) 3-(2-aminoethylamino)propyltrimethoxysilane or 3- 11 aminopropyltrimethoxysilane; 12 (D) water; 13 (I) epoxide silane; and 14 (H) lower alkanol. 1 Claim 14. The method of claim 2, wherein the oligomeric silane coating : 2 composition comprises, (XII) an aqueous coating composition formed by admixing 3 (A) at least one silane of the formula (1) 4 R'Si(OR); 1) 5 wherein © oom ~ RY isalower alkyl group, a phenyl group or a functional group includingat 7 least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional group; and 8 R? is a lower alkyl group; 9 (B) boric acid; 10 (C) at least one alkali component comprising an hydroxide or carbonate of 11 divalent metal; 12 (D) water; 13 (J) ethyl polysiloxane; and 14 (H) lower alkanol. 1 Claim 15. The method according to claim 1, for increasing the contact area 2 between first and second heat transfer surfaces in thermal contact with each other, 3 thereby improving the heat transfer efficiency across the thermally contacting heat 4 transfer surfaces, said method comprising, applying said low viscosity, penetrating 5 coating composition to the thermally contacting heat transfer surface of at least one of 6 said first and second heat transfer surfaces. 1 Claim 16. The method according to claim 15, wherein the coating 2 composition comprises an aqueous or non-aqueous oligomeric silane coating 3 composition formed by admixing

LIE 3 SW 4 (a) at least one silane of the formula (1) R'uSi(OR*)4.p (1 6 where R' represents a lower alkyl group, a C¢-Cj aryl group or a functional group 7 including at least one of vinyl, acrylic, amino, mercapto, or vinyl! chloride functional 8 groups; 9 (b) silane condensation catalyst, and (c) lower alkanol solvent, and optionally, one or more of 11 (d) colloidal aluminum hydroxide; 12 (¢) metal alcoholate of formula (2): 13 M(ORY), 2) 14 where M is a metal of valence 2, 3 or 4, or mixture of two or more such metals; R represents a lower alky! group; and, 16 m represents a number or 2, 3 or 4; 17 (f) silica component selected from the group consisting of alkali metal silicate, 18 ethyl orthosilicate, ethyl polysilicate, and colloidal silica dispersed in lower alkanol; 19 (g) color forming silanol condensation catalyst; (h) epoxysilane; 21 (i) ultrafine titanium dioxide ultraviolet light absorber; 22 (j) water; 23 (k) co-solvent; 24 and wherein the oligomeric coating composition is allowed to cure to a film thickness of from about 5 to about 150 millions of an inch, thereby filling any microvacancies 26 in said heat transfer surfaces. 1 Claim 17. The method according to claim 1, for improving the efficiency of 2 heat exchange apparatus of the type wherein a metal heat transfer surface is swaged or 3 force fit to a metal heat transfer fluid conveyance, said method comprising, applying 4 to the interface between the heat transfer surface and the conveyance said low 5 viscosity, penetrating coating composition whereby the coating composition will 6 displace gasses and liquids in said interface; and allowing the coating composition to 7 cure to a film thickness of from about 5 to about 150 millions of an inch, and fill any 8 microvacancies in said metal surfaces at said interface. 1 Claim 18. The method according to claim 17, wherein said coating 2 composition comprises an aqueous or non-aqueous oligomeric silane coating 3 composition formed by admixing (a) at least one silane of the formula (1)

‘ wWQ01/58972 PCT/US01/40052 vn 08 4 R':Si(OR%)4.n 1 where R' represents a lower alkyl group, a phenyl group or a functional group 6 including at least one of vinyl, acrylic, amino, mercapto, or vinyl chloride functional 7 groups; 8 (b) silane condensation catalyst, and 9 (c) lower alkanol solvent, and optionally, one or more of (d) colloidal aluminum hydroxide; 11 (e) metal alcoholate of formula (2): 12 M(OR?),,, 0) 13 where M is a metal of valence 2, 3 or 4, or mixture of two or more such metals; 14 R represents a lower alkyl group; and, m represents a number or 2, 3 or 4; 16 (f) a silica component selected from the group consisting of alkali metal 17 silicate, ethyl orthosilicate, ethyl polysilicate, and colloidal silica dispersed in lower 18 alkanol; 19 (g) color forming silanol condensation catalyst; Coes imme 2000-0 co (h)epoxysilane; = oc mms me me es re me rom 21 (1) ultrafine titanium dioxide ultraviolet light absorber; 22 (j) water; 23 (k) cosolvent.

Claim 19. The method according to claim 1, wherein said heat transfer 2 surface comprises a fin and tube heat transfer device. ] Claim 20. A heat transfer system comprising a metal heat transfer surface, 2 wherein said metal heat transfer surface is coated with a cured low viscosity, 3 penetrating, curable, reactive, film-forming, coating composition whereby the cured 4 coating composition has a film thickness of from about 5 to about 150 millions of an 5 inch, and fills any microvacancies in said metal surfaces.

Claim 21. The heat transfer system according to claim 20, wherein the heat 2 transfer surface of said heat transfer system comprises a fin and tube heat exchange 3 device. 1 Claim 22. The heat transfer system according to claim 20, wherein the heat 2 transfer surface comprises an evaporator, said coating being resistant to adhesion of 3 microorganisms.

PCT/US01/40052

23. A method as claimed in claim 1, substantially as herein described and illustrated.

24. A system as claimed in claim 20, substantially as herein described : and illustrated.

25. Anew method for improving efficiency of heat transfer, or a new heat transfer system, substantially as herein described. 41 AMENDED SHEET