Cation exchange Y zeolites as corrosion inhibitors
Zeolites free from heavy metal cations are ion-exchanged with alkaline earth metal cations. The exchanged zeolites provide corrosion resistance to paints for metals, especially ferrous metals, without environmental hazard caused by use of heavy-metal anti-corrosion materials such as lead, chromium, zinc, etc.
Latest W. R. Grace & Co.-Conn. Patents:
- SPHERICAL CATALYST COMPONENTS FOR OLEFIN POLYMERIZATION
- Production of high melt flow propylene-based polymer and product from same
- MODIFIED ZEOLITE CATALYST COMPOSITIONS AND METHODS OF USE
- STATIONARY PHASE FOR PURIFICATION OF CANNABIDIOL WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
- Propylene-ethylene copolymer compositions suitable for hot fill packaging of foodstuffs
This invention relates to the corrosion protection of metals, especially ferrous metals.
SUMMARY OF THE INVENTIONY zeolites (free from heavy metals) are ion-exchanged with ions of an alkaline earth metal. The cation exchanged Y zeolites provide corrosion resistance to paints for metals, especially ferrous metals, without health or environmental hazard caused by use of heavy-metal anti-corrosion materials such as lead, chromium, zinc, etc.
Background of the Invention
In order to protect iron and steel objects which are exposed to atmospheric corrosion, for example, automobiles, railroad equipment, ships, bridges, storage tanks, and the like, it is routine to coat them with several layers of paints, the first of which, the primer, acts as a sealing layer between the metal and the atmosphere. This primer typically contains rather large quantities of a corrosion-protective material which is intended to inhibit the harmful effect of sulfur, nitrogen, and carbon oxides in the air, as well as water vapor. Materials used for this purpose in the past are the heavy metal compounds, such as red lead, zinc, chromium oxide, and the like. These are generally quite effective; unfortunately they often offer severe health hazards and enduring harm to the environment.
Extensive attempts have been made to develop anti-corrosion materials free from heavy metals.
U.S. Pat. No. 2,913,419 discloses a sodium aluminum silicate coating on a particle core, ion-exchanged with calcium nitrate, as an anti-corrosion paint additive.
U.S. Pat. Nos. 2,848,346, 3,228,784 and 3,509,082 disclose amorphous sodium aluminosilicate zeolite pigments and pigment extenders which may be exchanged with cations such as hydrogen, lithium, calcium, barium, ammonium or cadmium.
U.S. Pat. No. 3,899,624 discloses ion exchange resins containing zinc as anti-corrosion additive for paints.
U.S. Pat. No. 4,419,137 (British Petroleum Co.) discloses silica gel ion-exchanged with various metals as corrosion-inhibitors for paints.
U.S. Pat. No. 4,687,595 discloses making corrosion-inhibiting particles comprising binding calcium ions to particles of silica or alumina of a certain surface area, followed by heating and water removal.
U.S. Pat. No. 4,738,720 describes anti-corrosive coating compositions which contain calcium exchanged zeolites.
U.K. Pat. No. 1,503,153 discloses zeolites ion-exchanged with heavy metals as corrosion-inhibitors for paints.
DETAILED DESCRIPTION OF THE INVENTIONThe invention is directed to a paint composition containing an alkaline earth metal exchanged Y zeolite as an anti-corrosion additive. The cation exchanged type zeolite is free from anti-corrosion heavy metals such as zinc, lead, and chromium. The invention includes the coatings resulting from the use of these paints, articles coated with the paints, and the method of rendering a paint non-corrosive by incorporating our treated zeolites into the paint.
The term "paint" is used in the generic sense and includes all liquid coating materials intended for application as protective coatings to surfaces, especially metal surfaces. Primers, sealants, and like coatings for iron, steel, and other ferrous metals are especially contemplated. The term "paint" also includes varnishes, enamels, and lacquers; pigmented and non-pigmented vehicles; and both oil- and water-based compositions.
Binders in these paints include drying oils, alkyd resins, epoxy resin esters, polyurethanes, phenol resins, urea resins, melamine resins, chlorinated rubbers, epoxide resins, polyamides, polyvinyl acetate, polyvinyl butyral, polyvinylidene fluoride, polyacrylic acid esters, and the like.
By heavy metals we mean those metals (as their compounds) customarily used in paint to inhibit corrosion on ferrous surfaces, such as Zn, Pb, Co, Cr and Mn.
The following examples illustrate without limiting the invention.
The cation exchanged Y zeolite which is used in the preparation of the paint compositions contemplated herein is obtained by ion-exchanging a Y zeolite (NaY), also referred to as Type Y crystalline aluminosilicate zeolite or synthetic faujasite, having the mol ratio chemical formula:
H.sup.+ /Na.sub.2 O: Al.sub.2 O.sub.3 : 3 to 50 SiO.sub.2, with a solution of the desired alkaline earth metal cation (preferably Ca.sup.++, Mg.sup.++ and/or Ba.sup.++).
The Y zeolite precursor zeolites may comprise a sodium Y zeolite (NaY) of the type described in U.S. Pat. No. 3,130,007, or alternatively the Y zeolite may comprise a thermally/chemically modified ultrastable Y zeolite as described in U.S. Pat. No. 3,293,192 and 3,449,070 (USY) a unit cell dimension of about 24.2 to 24.6 .ANG..
Subsequent to exchange with aqueous solution of metal cation salts such as magnesium, calcium, barium chlorides, sulfates and nitrates, the cation exchanged Y zeolites have from about 10 to 99 percent of the alkali metal and/or hydrogen cations substituted by desired metal cations. These exchanged Y zeolites are referred to herein as CaNaY, Mg H NaY, etc. to indicate the type of cation exchange achieved.
The cation exchanged Y zeolites are incorporated in paint compositions in amounts ranging from about 1 to 20 weight percent of the composition and more preferably from about 2 to 10 weight percent.
In order to obtain suitable performance as an anti-corrosion pigment the cation exchanged Y zeolite is comminuted, i.e. milled or ground, to a particle size range of 50 to 2 microns. The grinding of the Y zeolite component may take place prior to or during addition to the paint formulation.
In a typical procedure for preparing the cation exchanged Y zeolite used in the present invention, a sodium Y zeolite (NaY) having a silica to alumina ratio of about 4.5 and containing about 13 weight percent Na.sub.2 O is reacted with an aqueous exchange solution of alkali earth metal salt. The exchange solution may contain from about 1 to 25 weight percent of the desired metal salt. During the exchange procedure from about 2 to 10 parts exchange solution is combined with each part NaY at a temperature of 20.degree. to 100.degree. C. during which from 10 to 99 weight percent of the initial Na cation is substituted by alkaline earth metal cation. The resulting exchanged Y zeolite has the mol composition: 2 to 25 MO: 0.1 to 10 Na.sub.2 O:Al.sub.2 O.sub.3 :3 to 50 SiO.sub.2 wherein M represents Ca, Mg, and/or Ba.
The above described general procedure may be conducted using a variety (including mixtures) of alkaline earth metal salt solutions and various Y zeolites such as USY, HY zeolites as well as NaY zeolites.
EXAMPLE IPreparation of the various exchanged Y zeolites used in the subsequent Examples herein is described as follows:
Sample A comprises a hydrogen/sodium form of ultrastable zeolite Y (USY) which is exchanged to obtain various alkaline earth metal cation exchanged forms of USY. The ultrastable zeolite Y is prepared by ammonium exchange of a 5.0 SiO.sub.2 /Al.sub.2 O.sub.3 ratio zeolite Y to about 3.8 weight percent Na.sub.2 O, and then calcining in the presence of steam at about 732.degree. C.
Sample B was prepared by mixing 1000 g of USY (Sample A) in an exchange solution containing 1,798 g
of a 42 percent CaCl.sub.2 solution and 10,000 g H.sub.2 O for 1/2 hour at 66.degree. C. The slurry was filtered and washed with 8 1 66.degree. C H.sub.2 O. The exchange and wash steps were repeated, and the sample was dried overnight at 138.degree. C.
Sample C was prepared by adding 42.0 g magnesium oxide (MgO) to 2 1 H.sub.2 O, boiling one hour to hydrate the magnesia and then diluting to 4.0 1. To the above solution 1,000 g dry basis of USY (Sample A) was added, the slurry aged 1/2 hour at 66.degree. C., filtered, washed on the filter with 2 1 16.degree. C. H.sub.2 O and dried overnight at 138.degree. C.
Sample D was prepared by exchanging 1,000 g (dry basis) USY (Sample A) in a solution containing 10,000 g H.sub.2 O and 1,000 g barium chloride for 1/2 hour at 66.degree. C., filtered and rinsed on the filter with 2 1 66.degree. C. H.sub.2 O. The exchange was repeated, the slurry filtered, washed with 8 1 66.degree. C. H.sub.2 O and dried overnight at 138.degree. C.
The chemical analysis of the above exchanged Y zeolites is given in Table I.
TABLE I
__________________________________________________________________________
CHEMICAL ANALYSES OF ZEOLITES USED AS CORROSION
INHIBITORS FOR PRIMER COATINGS
Sample
A B C D
Composition
Na/H USY
Ca/Na USY
Mg/Na USY
Ba/Na USY
__________________________________________________________________________
TV (wt. %) 15.42 8.54 11.50 7.54
Na.sub.2 O (wt. %)
0.75 0.75 3.62 0.77
SiO.sub.2 (wt. %)
74.88 -- -- --
Al.sub.2 O.sub.3 (wt. %)
22.97 -- -- --
Surface Area, m.sup.2 /gm
-- 815 886 --
Metal Oxide (wt. %)
-- 3.19 (CaO)
2.78 (MgO)
7.13 (BaO)
__________________________________________________________________________
EXAMPLE II
Alkyd primers were prepared using the following ingredients:
______________________________________
Parts by Weight
______________________________________
Linseed/Soya Alkyd
15.9
Organic/Smectite Clay
2.0
Soya Lecithin .3
Mineral Spirits 2.8
Corrosion Inhibitor (as
4.5
identified in TABLE II)
Magnesium Silicate
14.0
Red Iron Oxide 24.8
______________________________________
The above mixture was dispersed on a high speed mixer for 15 minutes and milled to a particle size of 37 microns. Then the following ingredients were added with mixing.
______________________________________
Linseed/Soya Alkyd
28.2
6% Cobalt Napthenate
.3
6% Manganese Napthenate
.2
6% Zirconium Napthenate
.6
Anti Skinning Agent
.1
Mineral Spirits 6.3
______________________________________
The resulting coatings were then applied to phosphated steel panels at a dry film thickness of approximately 1.1 mils. The coated panels were then scribed and subjected to the standard salt spray test (ASTM-B117) for 500 hours. Results are as follows.
TABLE II
______________________________________
Test No.
Corrosion Inhibitor
Creepage from Scribe
______________________________________
1 Ba/Na USY (Sample D)
1/16"
2 Na/H USY (Sample A)
1/8" 8F blisters
3 Ca/Na USY (Sample B)
1/16"
4 Sodium Type A Zeolite
1/8" 8F blisters
5 Hydrotalcite 1/16"
______________________________________
The above data indicates that in test Nos. 1 and 3 the Ba/Na USY and Ca/Na USY corrosion inhibitors of the present invention are similar in effectiveness to the prior art inhibitor, Hydrotalcite. Na/H USY and sodium type A zeolite, which are not corrosion inhibitors of the present invention, are ineffective.
EXAMPLE IIIAnother oil alkyd primer was prepared with the following formulation:
______________________________________
Parts by Weight
______________________________________
Long Oil Soya Alkyd
11.5
Lecithin 0.47
Iron Oxide 1301 8.16
Dolomite 6.70
Barytes 18.50
Calcium Carbonate 2.55
Corrosion Inhibitor
various
(as identified in TABLE III)
Mineral Spirits 7.57
______________________________________
The above ingredients were ball milled to a maximum particle size of 37 microns. Then the following ingredients were added:
______________________________________
Castor Wax 0.30
______________________________________
Mill for an additional 30 minutes and add
______________________________________
Long Oil Soya 27.6
Mineral Spirits 5.10
24% Lead Napthenate
0.47
10% Cobalt Octoate 0.12
Anti-Skimming Agent
0.10
______________________________________
The primers were at a film thickness of three mils on an untreated street panel, scribed, and exposed for nine months in Curtis Bay, Md. (near Baltimore) at a 45' south elevation. The area is a highly industralized marine environment.
The following results were obtained:
TABLE III
__________________________________________________________________________
Wt. % Inhibitor
Table No.
Corrosion Inhibitor
In Primer
Creepage from Scribe
__________________________________________________________________________
1 Zinc Chromate
19 1/16" Dense blistering
along scribe
2 Barium Meta-Borate
19 1/16"+ Dense blistering
along scribe
3 Zinc Phosphate
19 1/16" + Dense blistering
along scribe
4 Ba/Na USY (Sample D)
11 1/16" Medium dense
blistering along scribe
5 Ba/Na USY (Sample D)
25 1/16" Few blisters
along scribe
6 Hydrotalcite
11 3/32" Medium blistering
along scribe
__________________________________________________________________________
The above results show that the corrosion inhibitor of the present invention (Test Nos. 4 & 5) are equivalent to or better than corrosion inhibitors of the prior art (Test Nos. 1, 2, 3 & 6).
EXAMPLE IVAnother example of this primer study is as follows: An epoxy urea primer such as the type used in the coil coating industry on 1303 galvanized steel was prepared and the corrosion inhibitor was varied. The basic formula is:
______________________________________
Epoxy Urea Coil Primer
Parts per Hundred
______________________________________
Epiclorohydrin bis-phenol resin
31.0
(35% solution)*
China Clay 14.5
Corrosion Inhibitor
4.3
(as identified in TABLE IV)
TiO.sub.2 15.2
Fumed Silica 0.8
Cellosolve Acetate 10.8
Urea Formaldehyde resin
11.3
Aromatic solvent 9.1
Organic modified smectite clay
0.4
Di-acetone alcohol 2.6
______________________________________
*35 parts Epon 1009 32.5 parts MIBK 32.5 parts Butyl Cellosolve
The primer was applied by spraying on 1303 galvanized steel to a dry film thickness of 0.4 mils. It was baked to a peak metal temperature of 450.degree. F. for one minute and scribed. The various primers were exposed 1000 hours in the salt spray test (ASTM-B117). The amount of corrosion inhibitor was held constant in this test at 4.3 weight percent.
The results are as follows:
TABLE IV
______________________________________
Creepage Blister-
Table No.
Corrosion Inhibiting Pigment
From Scribe
ing*
______________________________________
1 Zinc Hydroxy Phosphite
No Change 7F
2 Zinc Hydroxy Phosphite
3/16 6MD
3 Basic Lead Silica Chromate
No Change 8MD
4 Zinc Phosphate 1/4 8MD
5 Barium Metaborate 3/16 8MD
6 Strontium Chromate
No Change None
7 Ba/Na USY (Sample D)
1/8 8M
8 Ca/Na USY (Sample B)
3/16 8D
9 Mg/Na USY (Sample C)
1/4 6M
______________________________________
*Evaluated as follows: ASTM D71456
The above results indicate that paint formulations containing corrosion inhibitors of the present invention (Test Nos. 7, 8 & 9) are similar to most of those which contain conventional prior art inhibitors (Test Nos. 1-6).
A group of metal exchanged sodium Y zeolites (NaY) of the present invention were prepared as follows:
Mg/NaY (3.9 weight percent Na.sub.2 O-6.0 weight percent MgO) was prepared by adding 500 g dry basis (670.9 g as is) of Na-Y zeolite to 2.5 l 150.degree. F. H.sub.2 O containing 203.3 g magnesium chloride hydrate (MgCl.sub.2.6H.sub.2 O) for one-half hour at 150.degree. F., filtering and washing twice with 2.5 l 150.degree. F. H.sub.2 O. The exchange was repeated and the sieve then washed three times with 2.5 l 150.degree. F. H.sub.2 O. After calcination for 1 hour at 1000.degree. F., the exchange was repeated once again and the filter cake dried overnight at 250.degree. F.
Ba/Na Y (0.8 weight percent Na.sub.2 O-22.5 weight percent BaO) was prepared in the same way except that 256.1 g barium chloride hydrate (BaCl.sub.2.2H.sub.2 O) was used for each of the three exchanges.
Ca/Na Y (0.05 weight percent Na.sub.2 O-9.0 weight percent CaO) was also prepared in the same way as the Mg/Na Y except that 111 g anhydrous calcium chloride was used for each of the three exchanges.
EXAMPLE VA typical epoxy polyamide maintenance primer with the following composition was prepared and applied to sand blasted steel panels:
______________________________________
Part A
Epoxy Resin (Epiclorohydrin bis-phenol)
17.2
Methyl isobutyl ketone 2.8
Cellosolve 4.5
Corrosion Inhibitor 41.5
(as identified in TABLE V)
Iron Oxide (Mobay) 1.7
Magnesium Silicate 8.2
Urea Formaldehyde Resin 1.0
Xylol 8.4
Mica 325 mesh 2.6
Part B
Epoxy hardner-polyamide 12.0
______________________________________
The panels were aged for one week and subjected to salt spray exposure. The results are summarized in TABLE V.
TABLE V
__________________________________________________________________________
Epoxy Polyamide Primer - Sand Blasted Steel, 1000 Hours Salt Spray
Creepage
Film from
Thickness
Scribe
Blisters-
Test No.
Inhibitor Wt. %
Mils (Inches)
Appearance
__________________________________________________________________________
1 Zinc Phosphate
32 5.5 3/16 4M+- Along Scribe
2 Calcium Exchanged
23 6.8 1/8 Moderate Staining
Silica
3 Calcium Exchanged
13 6.4 3/32 Slight Staining
Silica
4 Ca/Na Y 23 4.8 1/8 Moderate Staining
5 Ca/Na Y 13 5.8 3/16 Moderate Staining
6 Ba/Na Y 23 5.9 3/16 Moderate Staining
7 Ba/Na Y 13 5.2 1/8 Slight Staining
8 Mg/Na Y 23 6.1 1/8 Slight Staining
9 Mg/Na Y 13 4.7 1/8 Slight Staining
__________________________________________________________________________
The above results show that the paint formulations containing corrosion inhibitors of the present invention (Test Nos. 4-9) are similar to the formulations which contained prior art corrosion inhibitors (Test Nos. 1-3).
Claims
1. A paint composition which contains an alkaline earth metal exchanged Y zeolite, said zeolite being substantially free from heavy metal cations.
2. The composition of claim 1 wherein the zeolite is ultrastable Y zeolite.
3. The composition of claim 1 or 2 wherein the alkaline earth metal cation is a member of the group Mg, Ca, Ba, and mixtures thereof.
4. The composition of claim 3 wherein the amount of alkaline earth cation in the zeolite expressed as oxide is within the range of about 3-25 weight percent.
5. The composition of claim 1 wherein the amount of zeolite is in the range 1 to 20 weight percent.
6. A metal substrate coated with the composition of claim 1.
7. A method for protecting a metal substrate from corrosion which comprises coating the substrate with the composition of claim 1.
| 2848346 | August 1958 | Bertorelli |
| 2913419 | November 1959 | Alexander |
| 3228784 | January 1966 | Mays et al. |
| 3509082 | April 1970 | Mays |
| 3899624 | August 1975 | Sutherland |
| 4220567 | September 2, 1980 | Kindervater et al. |
| 4419137 | December 6, 1983 | Cayless et al. |
| 4687595 | August 18, 1987 | Howes et al. |
| 4738720 | April 19, 1988 | Eckler et al. |
| 0025346 | February 1982 | JPX |
| 2084132 | April 1987 | JPX |
| 1015704 | January 1966 | GBX |
| 1503153 | August 1978 | GBX |
- Chem. Abst., 84:154070u, Kohlhass et al., Oct. 75.
Type: Grant
Filed: Jul 29, 1988
Date of Patent: Dec 4, 1990
Assignee: W. R. Grace & Co.-Conn. (New York, NY)
Inventors: Leon Kutik (Reisterstown, MD), Roger J. Lussier (Ellicott City, MD)
Primary Examiner: John S. Maples
Assistant Examiner: Valerie D. Fee
Attorney: Arthur P. Savage
Application Number: 7/226,020
International Classification: C04B 902;
