CA1074487A - Corrosion resistant coating material and method - Google Patents
Corrosion resistant coating material and methodInfo
- Publication number
- CA1074487A CA1074487A CA249,782A CA249782A CA1074487A CA 1074487 A CA1074487 A CA 1074487A CA 249782 A CA249782 A CA 249782A CA 1074487 A CA1074487 A CA 1074487A
- Authority
- CA
- Canada
- Prior art keywords
- primer
- flakes
- corrosion
- resistant coating
- coating composition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000005260 corrosion Methods 0.000 title claims abstract description 19
- 230000007797 corrosion Effects 0.000 title claims abstract description 16
- 238000000034 method Methods 0.000 title claims abstract description 7
- 238000000576 coating method Methods 0.000 title abstract description 14
- 239000011248 coating agent Substances 0.000 title abstract description 11
- 239000000463 material Substances 0.000 title abstract description 9
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 35
- 239000010935 stainless steel Substances 0.000 claims abstract description 35
- 239000000654 additive Substances 0.000 claims description 28
- 230000004888 barrier function Effects 0.000 claims description 15
- 239000011230 binding agent Substances 0.000 claims description 15
- 239000002184 metal Substances 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 230000000996 additive effect Effects 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 11
- 239000008199 coating composition Substances 0.000 claims description 10
- 238000009792 diffusion process Methods 0.000 claims description 10
- 229920005989 resin Polymers 0.000 claims description 9
- 239000011347 resin Substances 0.000 claims description 9
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 7
- NDKWCCLKSWNDBG-UHFFFAOYSA-N zinc;dioxido(dioxo)chromium Chemical compound [Zn+2].[O-][Cr]([O-])(=O)=O NDKWCCLKSWNDBG-UHFFFAOYSA-N 0.000 claims description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 230000006872 improvement Effects 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 5
- 229910000464 lead oxide Inorganic materials 0.000 claims description 5
- 230000000153 supplemental effect Effects 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- 239000011787 zinc oxide Substances 0.000 claims description 4
- 239000004593 Epoxy Substances 0.000 claims description 3
- 229920000180 alkyd Polymers 0.000 claims description 3
- 229920001971 elastomer Polymers 0.000 claims description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 3
- 239000011707 mineral Substances 0.000 claims description 3
- 229920001296 polysiloxane Polymers 0.000 claims description 3
- 235000015096 spirit Nutrition 0.000 claims description 3
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 3
- 229920002554 vinyl polymer Polymers 0.000 claims description 3
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 2
- 239000013528 metallic particle Substances 0.000 claims description 2
- YEXPOXQUZXUXJW-UHFFFAOYSA-N oxolead Chemical compound [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 claims 2
- 239000006185 dispersion Substances 0.000 claims 1
- 230000002708 enhancing effect Effects 0.000 claims 1
- 229920005749 polyurethane resin Polymers 0.000 claims 1
- 239000013589 supplement Substances 0.000 claims 1
- 239000002987 primer (paints) Substances 0.000 description 39
- 238000012360 testing method Methods 0.000 description 10
- 150000003839 salts Chemical class 0.000 description 8
- 239000007921 spray Substances 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 6
- 239000000049 pigment Substances 0.000 description 6
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 239000003973 paint Substances 0.000 description 3
- 229960001296 zinc oxide Drugs 0.000 description 3
- 235000014692 zinc oxide Nutrition 0.000 description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 231100000206 health hazard Toxicity 0.000 description 2
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 2
- 229920002803 thermoplastic polyurethane Polymers 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical class [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000383 hazardous chemical Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002674 ointment Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 235000010269 sulphur dioxide Nutrition 0.000 description 1
- 239000004291 sulphur dioxide Substances 0.000 description 1
- 230000009469 supplementation Effects 0.000 description 1
Abstract
CORROSION RESISTANT COATING MATERIAL AND METHOD Abstract of the Disclosure This disclosure deals with a novel corrosion-resistant primer or other coating material that has been found to become far more efficacious through the appro-priate addition of stainless steel planar flakes of rather critical geometry, dimensions and proportions.
Description
~74~
The present inVentiOn relates to corrosion-resis-tant coating materials such as primers and the like and to methods of preparing the same, being more particularly concexned with increasing the anti-corrosive effect of ~hose primers or other coatings having electrochemically active metal film additives and/or oxygen and moisture diffusion barrier additives.
Though the present invention will be dascribed in connection with the illustrative example of primer coatings, i.t is to be understood that the invention is applicable in the coating field genexally, wherever the same phenomena are desired; and, more particularly, in -~ the area of anti-corrosion coating~ For many years or-ganic and inorganic primers have been used, for example, in the painting of metal and the like for several func-tions of purposes, includin~ (1) a base for a final top coat, ~2) an anti-corrosive layer resistant to atmospheric pollution, (3) bonding to substrates, and (4) fox film strengthening. In connection with anti-corrosive applica-tions, the attack by oxygen and moisture often causes ; rusting o~ exposed metal surfaces. Atmospheric pollution containing sulphur dioxide and other gases similarly attacks exposed surfaces. While it is the function of an effective anti-corrosive primer to upgrade the protection by the coating to such vapors or conditions, the fact is that the problem of long life for such protective coatings still exists in the art and is still the subject of much research and de~elopment activity in view of the importance and high co~t involved.
As described, for example, in Metal Finishins ph~
' ~7~ 7 Guidebook Directory, published by Metals and Plastics Pub-lications, Inc., Westwood, N.J. 1972, commencing with p.586, there has been prior usage of electrochemically active anti-corrosive additives, such as zinc dust or other elemental zinc in high concentration; and also zinc chromate (sometimes known as zinc yellow), the higher lead oxides such as so-called red lead, and basic lead silico-chromates. These types of -anti-corrosive additives may be used in high concentration to provide a protective surface that prevents attack of the metal or other surface on which the coaking is applied.
Some of the above additives and others, such as red iron oxide, operate significantly as o~ygen and moisture diffusion barriers that provide some protection to the underlying metal or other surface. Current trends have limited the uses of-some of these materials, particularly those involving lead, however, as possible health hazards. Unfortunately, more-over, bridges and other outdoor structures, particularly I those in ocean and related environments, subject to salt spray or other serious atmospheric and environmental abuse, have to be scraped and repainted every few years at great expense and inconvenience despite the use of such primers as undercoats.
Numerous approaches have been tried and are still being tried to improve this situation and better salve this problem, including upgrading the paint materials with alkyd epoxy, chlorinated rubber, silicone, vinyl and poly-urethane resins and the like; but these have not adequately solved the problem. As described in an article entitled "Stainless Steel Paints", appearing in Metal Finishing, Yebrgary, 1967, comme=ci=q with pa9e 6-, it has bee= sug~
_ z _ , ;
~ ~.
ph~
~ .
~7 4~
gested that the anti-corrosive pigments of corrosion in-hibitive primers might be combined with conventional stain~
less steel particle pigments, such as those marketed under the trademark "Stay-Steel" by Chas. Pfizer & Co., into a one-coat primer top coat that might offer stainless steel reinforcement. In practice, however, it has not been found that such proposal, with conventional stainless steel particles so admixed into a single coat, has actually served significantly to improve the difficulty. The above~
mentioned article points out that such a single coat proposal, had not heretofore in practice been able fully to achieve ..
' ,; :' - ' . ' ' , .
_ 3 - :
ph b~
~7~
the desired results.
Underlying the present invention, however, is the unexpected discovery that, if stainless steel particles are rather critically geometically reshaped and dimenisoned, and appropriately admixed, they can indeed be dispersed in anti-corrosive primer binders as a single coat, with a rather re-markable synergistically obtained improved protection per-formance.
The present invention, therefore, has as one of its primary objectives the provision of a new and improved corrosion resistant coating material that employs such critically dimensioned stainless steel material, and improved methods of preparing the same, greatly to improve the protective charac-teristîcs of a single coatine and the like.
In one particular aspect the present invention provides in a corrosion-resistant coating composition comprising a :
primer selected from the group consisting of organic and inorganic binders and metallic particles dispersed therethrough;
the improvement comprising, as said particles, stainless steel planar flakes of thicknes6 of the order of 1/3 of a micron and of surface dimensions largely of the order of 10 to ~0 microns and in amounts of at least 1 pound per U.S. gallon of primer.
In another particular aspect the present invention provides in a method of increasing the corrusion-resistant effect of anti-corrosive primer resins containing at least one of :
electrochemically active metal film additives and oxygen moisture diffusion barriers; the improvement comprising adding to the primer resin stainless steel planar flakes in amounts of ;~
at least one pound per U.S. gallon of primer resin, said flakes having a thickness of the order of 1/3 of a micron and surface dimensions largely of the order of 10 to ~Q microns, and ; dispersing said flakes through the primer resin to provide a j l / ~_ ~ .
~,,~ .
.
; , .: :
~7~'7 supplemental protective surface that cooperates with such metal film additives to increase the electrochemical protection thereof and cooperates with said diffusion barriers to provide a supplemental flake barrier.
Other and further objects will be explained hereinafter and are more particularly delineated in the appended claims.
As above stated, it has been quite accidently discovered that the use of stainless steel particles in extremely thin planar flake form, as distinguished from the arbitary shape, somewhat spherical or other discreet particle size, as in the prior art stainless steel pigments, including those before-mentioned, vastly improves the protective quality of primer binders and similar coatings in a manner that cannot be attained with stainless steel particles of the shapes and sizes previously used.
When such prior art stainless steel pigments are added to conventional red primers containing 2inc chromates, zinc - oxide and red iron oxide, for example, and the same is applied as a primer to steel surfaces and exposed to rigid salt spray attack over prolonged periods of time, the coating has been found seriously to blister and rust to about the same degree as the primer alone without the added stainless steel particles.
When, however, the same amount of stainless steel was added to and dispersed in the primer in exactly the same conditions of test, but with the stainless steel in the form of planar flakes of the above-mentioned rather critical dimensions and configuration, vastly improved, and indeed in some cases, negligible blistering and rusting results were obtained.
Specifically, using the before-mentioned anti-rust .: .
jl/ -5-.
~7~
primer of the type marketed by Sears under No. 68~92, with one pound of the said "Stay-Steel" stainless steel pigment per gallon of primer, salt spray testing was conducted on steel plates in accordance with ASTM Test Bi, B117 (100F at ~
salt spray). This same test was performed with exactly thç
same weight of stainless steel flakes having an average thick- -:
ness of 0.34 or 1/3 micron and surface climensions of the flakes largely in the range of f.rom 10-40 microns ~with approximately 33% being in the range of 2Q-30 microns, about 14% from 30-40 .microns and about 30% between 10 and 20 microns), with the - ~ .
surface dimensions of the flakes being very large compared to the minute thickness of the fla~es. Additionally, the .same test was performed with the anti-corrosive primer alone absent ~ :.
of any type of stainless steel additive.
On a scale of 10 established by the said test, a~te~ ~: .
140 hours oE salt spray exposure, the plates coated with the primer alone and with the primer and "Stay-Steel" particles -showed the same degradation as follows: blistering down to 7; :
and rusting down to S. In connection with the primer contain- ;
lng the stainless steel planar flakes, however,~the blistering was extremely slight, at 9; and the rasting was also slight, :
at 8. A~ter 290 hours of the salt spray exposure, the plates -:
with the primer alone showed a degradation of blistering to ~, :
and a rusting down to 3; being somewhat better than the primer ~ :
with the "Stay-Steel" particles, which degraded to.a blister- :
ing o~ 4 and a rusting of 3. The 290 hour test with the before mentioned stainless steel planar flakes additive, however, still : showed but slight blistering at 8, and very slight degradation in rusting at 7.
Other salt spray tests with zinc chromate primer ~7~
similarly showed remarkably improved rus-t inhibiting perfor-mance in accordance with the invention.
It was further found that while improved results could be obtained within a rather wide range of variation of stainless steel flake additive proportions, if the weight were reduced substantially below one pound of stainless steel addi-tive per U. S. gallon of primer, the results were closer to the performance of the primer alone; such that at least of the order of approximately one pound of stainless steel flakes .additive per gallon of primer has been determined to be desirable for the more spectacular improvement results above delineated.
While there is no intention to be bound by theoretical explanations, correct or incorrect, it being sufficient merely to describe the construction that has been found to work in practice, it may be helpful to consider what is believed to be a possible explanation for this unexpected improved resul~. In the case of anti-corrosive primer additives of the type that form metallic film (such as el0mental zinc additives before-mentioned and the like), it appears that those partioles that contact the stainless steel flakes have a vastly im-proved or enhanced electrochemical reaction beyond that attain-able with the metallic film alone in the absence of saia flakes, such that a more effective protective surface is thereby attained. This, of course, is supplimental to the inherent protection provided by the surface formed by the planar flakes of stainless steel. In connection, moreover, with anti-corrosive additives (such as iron oxide, lead oxide and the like~, which appear to protect at least in part as a result of forming an oxygen and moisture diffusion barrier, the contacting of the same with the stainless steel f~lake ph~
barrier appears -to provide a supplemental and vastly improved difEusion oarrier effect1 with the barriers cohering in im~
proved fashion.
A second example of efficacious use of the invention is the use of substantially one pound of the said critically dimensioned stainless steel planar flakes in a gallon of Irco zinc chromate primer in an organic binder, where no evidence o~ rust even started to appear until slightly over 300 hours of intense salt spray testing.
. As a further example, the successful tests first described in connection with tbe Sears primer and its anti-corrosive zinc chromate, zinc oxide and red iron oxide addi-tives were conducted with the stainless steel planar flakes of the critical shape and dimensions before detailed dis-persed in the organic primer binder after the flakes had been formed with mineral spirits into a paste. The paste was mixed rapidly into the binder containing the anti-corrosive elements above mentioned.
As still another example, the primer organic binder with which the said stainless steel flakes are mixed =ay com-prise a binder material seleoted from the group consisting o~
alkyd, epoxy, vinyl, silicone, chlorinated rubber, and poly- ;
urethane resins.
As still a further illustration, the binder receivlng the stainless steel flakes may be inorganic, as of zinc alkali silicates.
As other examples, in addition to the elemental zinc, zinc chromate and zinc oxide pigment additives for anti-corro-sion purposes, where health hazard restrictions are not appli-cable, lead o~ide and lead silico-chromate may be used, as well , - 8 ~
'., ph:~S`~
' 7~
as combinations of all of the above with the flakes.
As still another example, diffusion barrier supple-mentation with the said stainless steel flakes may be attained with iron oxide and lead oxide additives.
In all of the above cases, the conventional electro-chemically actlve anti-corrosion metal film additives and/or the diffusion barrier additives were employed in precisely the conventional commercial proportions that have been used for many years and are currently used in the conventional organic and inorganic primer binders, such as the specific examples ,~
above referenced.
~ s before stated, while the invention is particularly ;-- efficacious in its application to a one-coat anti-corrosive stainless steel additive coating, it is clearly applicable with ' other coatings wherein the improvement herein attained may be desired. It should be noted that the invention in no way' ' -' modifies the physical and other properti~es of the primer or ' other coating so that paint or oth~e~r,~r,e,at,ment may be applied as in present-day operation. Further modifications will occur to those skilled in this art and all such are considered to fall within the spirit and scope of tha invention as defined - in the appended claims.
~ .
' ' ., ~, . .
':
' ' '::
_ 9 _ ,., :.::
ph:b'ii' ', : . : :, . ' : ~:
' ~ ~ ' ...... ' . ~ ' : '
The present inVentiOn relates to corrosion-resis-tant coating materials such as primers and the like and to methods of preparing the same, being more particularly concexned with increasing the anti-corrosive effect of ~hose primers or other coatings having electrochemically active metal film additives and/or oxygen and moisture diffusion barrier additives.
Though the present invention will be dascribed in connection with the illustrative example of primer coatings, i.t is to be understood that the invention is applicable in the coating field genexally, wherever the same phenomena are desired; and, more particularly, in -~ the area of anti-corrosion coating~ For many years or-ganic and inorganic primers have been used, for example, in the painting of metal and the like for several func-tions of purposes, includin~ (1) a base for a final top coat, ~2) an anti-corrosive layer resistant to atmospheric pollution, (3) bonding to substrates, and (4) fox film strengthening. In connection with anti-corrosive applica-tions, the attack by oxygen and moisture often causes ; rusting o~ exposed metal surfaces. Atmospheric pollution containing sulphur dioxide and other gases similarly attacks exposed surfaces. While it is the function of an effective anti-corrosive primer to upgrade the protection by the coating to such vapors or conditions, the fact is that the problem of long life for such protective coatings still exists in the art and is still the subject of much research and de~elopment activity in view of the importance and high co~t involved.
As described, for example, in Metal Finishins ph~
' ~7~ 7 Guidebook Directory, published by Metals and Plastics Pub-lications, Inc., Westwood, N.J. 1972, commencing with p.586, there has been prior usage of electrochemically active anti-corrosive additives, such as zinc dust or other elemental zinc in high concentration; and also zinc chromate (sometimes known as zinc yellow), the higher lead oxides such as so-called red lead, and basic lead silico-chromates. These types of -anti-corrosive additives may be used in high concentration to provide a protective surface that prevents attack of the metal or other surface on which the coaking is applied.
Some of the above additives and others, such as red iron oxide, operate significantly as o~ygen and moisture diffusion barriers that provide some protection to the underlying metal or other surface. Current trends have limited the uses of-some of these materials, particularly those involving lead, however, as possible health hazards. Unfortunately, more-over, bridges and other outdoor structures, particularly I those in ocean and related environments, subject to salt spray or other serious atmospheric and environmental abuse, have to be scraped and repainted every few years at great expense and inconvenience despite the use of such primers as undercoats.
Numerous approaches have been tried and are still being tried to improve this situation and better salve this problem, including upgrading the paint materials with alkyd epoxy, chlorinated rubber, silicone, vinyl and poly-urethane resins and the like; but these have not adequately solved the problem. As described in an article entitled "Stainless Steel Paints", appearing in Metal Finishing, Yebrgary, 1967, comme=ci=q with pa9e 6-, it has bee= sug~
_ z _ , ;
~ ~.
ph~
~ .
~7 4~
gested that the anti-corrosive pigments of corrosion in-hibitive primers might be combined with conventional stain~
less steel particle pigments, such as those marketed under the trademark "Stay-Steel" by Chas. Pfizer & Co., into a one-coat primer top coat that might offer stainless steel reinforcement. In practice, however, it has not been found that such proposal, with conventional stainless steel particles so admixed into a single coat, has actually served significantly to improve the difficulty. The above~
mentioned article points out that such a single coat proposal, had not heretofore in practice been able fully to achieve ..
' ,; :' - ' . ' ' , .
_ 3 - :
ph b~
~7~
the desired results.
Underlying the present invention, however, is the unexpected discovery that, if stainless steel particles are rather critically geometically reshaped and dimenisoned, and appropriately admixed, they can indeed be dispersed in anti-corrosive primer binders as a single coat, with a rather re-markable synergistically obtained improved protection per-formance.
The present invention, therefore, has as one of its primary objectives the provision of a new and improved corrosion resistant coating material that employs such critically dimensioned stainless steel material, and improved methods of preparing the same, greatly to improve the protective charac-teristîcs of a single coatine and the like.
In one particular aspect the present invention provides in a corrosion-resistant coating composition comprising a :
primer selected from the group consisting of organic and inorganic binders and metallic particles dispersed therethrough;
the improvement comprising, as said particles, stainless steel planar flakes of thicknes6 of the order of 1/3 of a micron and of surface dimensions largely of the order of 10 to ~0 microns and in amounts of at least 1 pound per U.S. gallon of primer.
In another particular aspect the present invention provides in a method of increasing the corrusion-resistant effect of anti-corrosive primer resins containing at least one of :
electrochemically active metal film additives and oxygen moisture diffusion barriers; the improvement comprising adding to the primer resin stainless steel planar flakes in amounts of ;~
at least one pound per U.S. gallon of primer resin, said flakes having a thickness of the order of 1/3 of a micron and surface dimensions largely of the order of 10 to ~Q microns, and ; dispersing said flakes through the primer resin to provide a j l / ~_ ~ .
~,,~ .
.
; , .: :
~7~'7 supplemental protective surface that cooperates with such metal film additives to increase the electrochemical protection thereof and cooperates with said diffusion barriers to provide a supplemental flake barrier.
Other and further objects will be explained hereinafter and are more particularly delineated in the appended claims.
As above stated, it has been quite accidently discovered that the use of stainless steel particles in extremely thin planar flake form, as distinguished from the arbitary shape, somewhat spherical or other discreet particle size, as in the prior art stainless steel pigments, including those before-mentioned, vastly improves the protective quality of primer binders and similar coatings in a manner that cannot be attained with stainless steel particles of the shapes and sizes previously used.
When such prior art stainless steel pigments are added to conventional red primers containing 2inc chromates, zinc - oxide and red iron oxide, for example, and the same is applied as a primer to steel surfaces and exposed to rigid salt spray attack over prolonged periods of time, the coating has been found seriously to blister and rust to about the same degree as the primer alone without the added stainless steel particles.
When, however, the same amount of stainless steel was added to and dispersed in the primer in exactly the same conditions of test, but with the stainless steel in the form of planar flakes of the above-mentioned rather critical dimensions and configuration, vastly improved, and indeed in some cases, negligible blistering and rusting results were obtained.
Specifically, using the before-mentioned anti-rust .: .
jl/ -5-.
~7~
primer of the type marketed by Sears under No. 68~92, with one pound of the said "Stay-Steel" stainless steel pigment per gallon of primer, salt spray testing was conducted on steel plates in accordance with ASTM Test Bi, B117 (100F at ~
salt spray). This same test was performed with exactly thç
same weight of stainless steel flakes having an average thick- -:
ness of 0.34 or 1/3 micron and surface climensions of the flakes largely in the range of f.rom 10-40 microns ~with approximately 33% being in the range of 2Q-30 microns, about 14% from 30-40 .microns and about 30% between 10 and 20 microns), with the - ~ .
surface dimensions of the flakes being very large compared to the minute thickness of the fla~es. Additionally, the .same test was performed with the anti-corrosive primer alone absent ~ :.
of any type of stainless steel additive.
On a scale of 10 established by the said test, a~te~ ~: .
140 hours oE salt spray exposure, the plates coated with the primer alone and with the primer and "Stay-Steel" particles -showed the same degradation as follows: blistering down to 7; :
and rusting down to S. In connection with the primer contain- ;
lng the stainless steel planar flakes, however,~the blistering was extremely slight, at 9; and the rasting was also slight, :
at 8. A~ter 290 hours of the salt spray exposure, the plates -:
with the primer alone showed a degradation of blistering to ~, :
and a rusting down to 3; being somewhat better than the primer ~ :
with the "Stay-Steel" particles, which degraded to.a blister- :
ing o~ 4 and a rusting of 3. The 290 hour test with the before mentioned stainless steel planar flakes additive, however, still : showed but slight blistering at 8, and very slight degradation in rusting at 7.
Other salt spray tests with zinc chromate primer ~7~
similarly showed remarkably improved rus-t inhibiting perfor-mance in accordance with the invention.
It was further found that while improved results could be obtained within a rather wide range of variation of stainless steel flake additive proportions, if the weight were reduced substantially below one pound of stainless steel addi-tive per U. S. gallon of primer, the results were closer to the performance of the primer alone; such that at least of the order of approximately one pound of stainless steel flakes .additive per gallon of primer has been determined to be desirable for the more spectacular improvement results above delineated.
While there is no intention to be bound by theoretical explanations, correct or incorrect, it being sufficient merely to describe the construction that has been found to work in practice, it may be helpful to consider what is believed to be a possible explanation for this unexpected improved resul~. In the case of anti-corrosive primer additives of the type that form metallic film (such as el0mental zinc additives before-mentioned and the like), it appears that those partioles that contact the stainless steel flakes have a vastly im-proved or enhanced electrochemical reaction beyond that attain-able with the metallic film alone in the absence of saia flakes, such that a more effective protective surface is thereby attained. This, of course, is supplimental to the inherent protection provided by the surface formed by the planar flakes of stainless steel. In connection, moreover, with anti-corrosive additives (such as iron oxide, lead oxide and the like~, which appear to protect at least in part as a result of forming an oxygen and moisture diffusion barrier, the contacting of the same with the stainless steel f~lake ph~
barrier appears -to provide a supplemental and vastly improved difEusion oarrier effect1 with the barriers cohering in im~
proved fashion.
A second example of efficacious use of the invention is the use of substantially one pound of the said critically dimensioned stainless steel planar flakes in a gallon of Irco zinc chromate primer in an organic binder, where no evidence o~ rust even started to appear until slightly over 300 hours of intense salt spray testing.
. As a further example, the successful tests first described in connection with tbe Sears primer and its anti-corrosive zinc chromate, zinc oxide and red iron oxide addi-tives were conducted with the stainless steel planar flakes of the critical shape and dimensions before detailed dis-persed in the organic primer binder after the flakes had been formed with mineral spirits into a paste. The paste was mixed rapidly into the binder containing the anti-corrosive elements above mentioned.
As still another example, the primer organic binder with which the said stainless steel flakes are mixed =ay com-prise a binder material seleoted from the group consisting o~
alkyd, epoxy, vinyl, silicone, chlorinated rubber, and poly- ;
urethane resins.
As still a further illustration, the binder receivlng the stainless steel flakes may be inorganic, as of zinc alkali silicates.
As other examples, in addition to the elemental zinc, zinc chromate and zinc oxide pigment additives for anti-corro-sion purposes, where health hazard restrictions are not appli-cable, lead o~ide and lead silico-chromate may be used, as well , - 8 ~
'., ph:~S`~
' 7~
as combinations of all of the above with the flakes.
As still another example, diffusion barrier supple-mentation with the said stainless steel flakes may be attained with iron oxide and lead oxide additives.
In all of the above cases, the conventional electro-chemically actlve anti-corrosion metal film additives and/or the diffusion barrier additives were employed in precisely the conventional commercial proportions that have been used for many years and are currently used in the conventional organic and inorganic primer binders, such as the specific examples ,~
above referenced.
~ s before stated, while the invention is particularly ;-- efficacious in its application to a one-coat anti-corrosive stainless steel additive coating, it is clearly applicable with ' other coatings wherein the improvement herein attained may be desired. It should be noted that the invention in no way' ' -' modifies the physical and other properti~es of the primer or ' other coating so that paint or oth~e~r,~r,e,at,ment may be applied as in present-day operation. Further modifications will occur to those skilled in this art and all such are considered to fall within the spirit and scope of tha invention as defined - in the appended claims.
~ .
' ' ., ~, . .
':
' ' '::
_ 9 _ ,., :.::
ph:b'ii' ', : . : :, . ' : ~:
' ~ ~ ' ...... ' . ~ ' : '
Claims (11)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a corrosion-resistant coating composition comprising a primer selected from the group consisting of organic and inorganic binders and metallic particles dispersed therethrough;
the improvement comprising, as said particles, stainless steel planar flakes of thickness of the order of 1/3 of a micron and of surface dimensions largely of the order of 10 to 40 microns and in amounts of at least 1 pound per U.S. gallon of primer.
the improvement comprising, as said particles, stainless steel planar flakes of thickness of the order of 1/3 of a micron and of surface dimensions largely of the order of 10 to 40 microns and in amounts of at least 1 pound per U.S. gallon of primer.
2. A corrosion-resistant coating composition as claimed in Claim 1 and in which said primer further contains an anti-corrosive additive for forming a metallic film that contacts said flakes and, by electrochemical action, forms a protective surface additional to that formed by the said planar flakes, the contact between the said film and flakes enhancing said electrochemical action beyond that attainable with the additive alone in the absence of said flakes.
3. A corrosion-resistant coating composition as claimed in Claim 2 and in which said additive is selected from the group consisting of elemental zinc, zinc chromate, zinc oxide, lead oxide, lead silico-chromate, and combinations thereof.
4. A corrosion-resistant coating composition as claimed in Claim 1 and in which said primer further contains an anti-corrosive additive for forming an oxygen and moisture diffusion barrier that contacts said flakes and supplements the barrier effect of said planar flakes.
5. A corrosion-resistant coating composition as claimed in Claim 4 and in which said additive is selected from the group consisting of iron oxide and lead oxide.
6. A corrosion-resistant coating composition as claimed in Claim 1 and in which said primer binder comprises an organic resin.
7. A corrosion-resistant coating composition as claimed in Claim 6 and in which said primer binder is selected from the group consisting of alkyd, epoxy, vinyl, silicone, chlorinated rubber and polyurethane resins.
8. A corrosion-resistant coating composition as claimed in Claim 1 and in which said primer binder comprises zinc-alkali silicates.
9. A corrosion resistant coating composition as claimed in Claim 1 and in which said flakes are initially formed as a paste in mineral spirits prior to dispersion in the primer binder.
10. In a method of increasing the corrosion-resistant effect of anti-corrosive primer resins containing at least one of electrochemically active metal film additives and oxygen moisture diffusion barriers; the improvement comprising adding to the primer resin stainless steel planar flakes in amounts of at least one pound per U.S. gallon of primer resin, said flakes having a thickness of the order of 1/3 of a micron and surface dimensions largely of the order of 10 to 40 microns, and dispersing said flakes through the primer resin to provide a supplemental protective surface that cooperates with such metal film additives to increase the electrochemical protection thereof and cooperates with said diffusion barriers to provide a supplemental flake barrier.
11. A method as claimed in Claim 10 and in which said stainless steel flakes are added in the form of a mineral spirits paste.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA249,782A CA1074487A (en) | 1976-04-07 | 1976-04-07 | Corrosion resistant coating material and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA249,782A CA1074487A (en) | 1976-04-07 | 1976-04-07 | Corrosion resistant coating material and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074487A true CA1074487A (en) | 1980-03-25 |
Family
ID=4105662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA249,782A Expired CA1074487A (en) | 1976-04-07 | 1976-04-07 | Corrosion resistant coating material and method |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1074487A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112071946A (en) * | 2019-05-21 | 2020-12-11 | 北京铂阳顶荣光伏科技有限公司 | Preparation method of thin-film solar cell |
-
1976
- 1976-04-07 CA CA249,782A patent/CA1074487A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112071946A (en) * | 2019-05-21 | 2020-12-11 | 北京铂阳顶荣光伏科技有限公司 | Preparation method of thin-film solar cell |
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