JPS608062B2 - Anti-corrosion paint composition - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD This invention relates to corrosion-inhibiting coating compositions.

Anti-corrosion coatings protect metal structures, piping, heating devices and mechanical parts, etc. from the aggressive effects of the atmosphere (of any humidity) and liquid media (tap water, water injection and process water, organic liquids, etc.) as well as hot gas flows. It has a wide range of uses in protecting against attributable corrosion.

Paints and varnishes currently used for corrosion protection of metals are based on organic compounds such as pentathalic, chlorinated vinyl chloride, and the like. However, these paints are susceptible to aging and deterioration which is exacerbated by factors such as high temperature, humidity and sunlight. Additionally, these compositions contain toxic, hazardous, and volatile organic solvents such as toluene, xylene, and the like. It is known in the art to use compositions containing phosphate binders to improve their protective properties and extend their service life.

Thus, known in the art are inorganic-based anticorrosion coating compositions incorporating phosphate ions, chromate and aluminum powder (see U.S. Pat. No. 3,248,251); requires heat treatment of the paint, which is carried out at temperatures ranging from 191 to 5380C.

Furthermore, the coatings obtained have relatively low corrosion protection in liquid media or when used outdoors. Compositions for the production of anticorrosive paints containing magnesium hydrogen phosphate, anhydrous aluminum chromate, orthophosphoric acid and liquid glass are known (see US Pat. No. 3,460,955).
.

This prior art composition results from a complex technique of its deposition onto metals, including prolonged stepwise heat treatment at high temperatures (42 o), which is necessary for curing of the composition. It has certain disadvantages. Paints made with this composition also have relatively low corrosion protection.

Anticorrosion coating compositions containing polyvalent metal molybdate and phosphate compounds in an aqueous dispersion of a polymeric organic compound are also known (see US Pat. No. 3,528,86).

The disadvantages of these compositions may be illustrated by the fact that the molybdenum compounds used are difficult to obtain and expensive, and the resulting coatings have relatively low corrosion protection. Add these to the list below. Its use is not recommended without the application of a protective layer of tints and varnishes.

Aqueous solutions of molybdates of elements of groups 1 and B of the periodic table (concentrations below 0.5 mol/mole) and aqueous solutions of high molecular weight organic compounds (0.05 to 45% by weight) or Anticorrosive paint compositions comprising emulsions of methacrylate, polyptadine-styrene, etc.) are known.

After heat treatment of such a paint, a thin anticorrosive film with a thickness of 2 to 4 m is obtained (Japanese Patent No. 6846).
(see specification). The coatings obtained have only low insulation properties due to the small thickness of the layers produced in this way.
When using such a composition, 260-300oo
heat treatment at a temperature of Furthermore, molybdenum compounds are used in such compositions, which are difficult to obtain and expensive. One of the objects of the present invention is to provide high adhesion to metal surfaces and without the need for heat treatment of the coating at temperatures above 150-160 q○, without containing difficult-to-obtain and expensive components, and without requiring heat treatment of the coating at temperatures above 150-160 q○. An object of the present invention is to provide an anticorrosion coating composition that guarantees the production of a protective film having a thickness of 70 to 10 skin thickness or more. For this purpose, an anticorrosive coating composition containing a phosphate binder consisting of an aqueous solution of a biphosphate in which calcium, aluminum, trivalent chromium, hexavalent chromium are present, and an aqueous dispersion of a polymeric organic compound, pigment, nitric acid Contains sodium and water,
This is achieved by an anticorrosive coating composition in which these components are present in the following proportions in parts by weight: phosphate ions (as P2Q) 6.5-7.9 calcium ions
0.36-0.7 aluminum ion
0.25-0.426 valent chromium ion
0.95-1.453 trivalent chromium ion
0.52-0.7 pigment
9.0-25.0 Aqueous dispersion of organic polymer compound 1.75-28.0 (dry basis) Sodium nitrate 0.1-0.5 Water (
(including water in the aqueous dispersion) 23.25-57.0 The phosphate ions in the composition are present in the form of orthophosphoric acid partially neutralized with calcium, aluminum and chromium ions.

The presence of phosphate ions in the composition according to the invention provides favorable conditions for higher adhesion between the coating film produced and the substrate upon application of the coating. As the content of phosphate ions decreases below 6.5 parts by weight, the adhesion of the coating to metal decreases, while its content decreases below 7.5 parts by weight. As the weight increases above the weight part, the porosity of the coating increases as a result of strong evolution of hydrogen by reaction with the underlying iron. The presence of calcium ions in the coating composition makes it possible to shorten the range of dehydration of the partially neutralized solution of orthophosphoric acid during the heat treatment of the coating, thereby reducing the amount of water in the system at temperatures in the range of 150 to 160 q0. giving rise to the formation of water-resistant compounds.

At a calcium ion content below 0.3 parts by weight, the removal effect of structured water at a temperature of 150-160°C is not achieved, while at a calcium ion content above 0.7 parts by weight its departure The solution becomes heterogeneous, which further causes its crystallization.

The introduction of aluminum ions ensures a higher degree of neutralization of the orthophosphoric acid and provides conditions for the formation of aluminum and chromium ions in the solution.

At aluminum ion contents below 0.25 parts by weight, the acidity of the partially neutralized orthophosphoric acid starting solution increases;
On the other hand, at contents above 0.42 parts by weight, the viscosity of the solution increases considerably and the working properties of the starting mixture are impaired.

The role of chromium ions in anticorrosion coating compositions is to passivate the metal upon application of the coating and is an armor ion that promotes the resistance, stability and film-forming properties of the neutralized 3P04 aqueous solution. ensure the conditions for the formation of

(Cr-16) content below 0.95 parts by weight and 0
．． At a content below 52 parts by weight (Cr30), optimum conditions for coating formation are not guaranteed due to the absence of a passive film on the metal, and the insulating strength of the coating is reduced. Furthermore, the safety of the starting composition is also compromised. 1.45
A content above 0.7 parts by weight (Cr30) and a content above 0.7 parts by weight result in a higher permeability and a higher porosity of the coating for the electrolyte, thus Its protective power is impaired and the toxicity of the coating manufacturing and application process is increased.

The function of the pigment is to form a strong framework and structure of the film coating by superficial acid-based interactions with P04 at the interphase boundaries. 9. Pigment contents below 2 parts by weight do not guarantee the provision of a strong and durable coating and increase its porosity. On the other hand, increased pigment content improves the elasticity of the coating film.
Reduces flexibility and impact strength. The pigments used are aluminum, zinc, iron oxide, titanium dioxide, zircon or talc. The formulation of aqueous dispersions of polymeric organic compounds is associated with the need to thicken the resulting coating, improving its impermeability to moisture, steam and gases, and to aqueous electrolyte solutions.

Furthermore, the presence of the aqueous dispersion of polymeric organic compounds imparts elasticity and flexibility to the protective coating. 5. The effect of increasing elasticity and flexibility is not achieved with aqueous polymeric organic compound dispersion contents below 40 parts by weight, while 40 parts by weight. At a content of the aqueous polymeric organic compound dispersion above 20 parts by weight, the adhesion of the film to metal is reduced and the physico-mechanical properties of the resulting coating are impaired.

The content of the polymeric organic compound in the aqueous dispersion is 35 to 7
can be varied within a wide range in weight percent without affecting the protective properties of the coating. Therefore, the amount of the aqueous polymeric organic compound dispersion in the composition of the present invention is 1.75 to 28% on a dry matter basis. parts by weight. Examples of aqueous polymeric organic compound dispersions include polymethyl methacrylate, polyepoxidized methyl methacrylate, poly(butadiene-styrene), polybutadiene carboxylate, copolymer of butadiene and methacrylic acid, polyvinylidene chloride, polyvinyl acetate, Pyridine-containing latex, epoxidized polyvinyl acetate, polystyrene carboxylate,
Polyurethane, polysilicon acrylate, polydivinylstyrene are used in the present invention. The presence of sodium nitrate in the anticorrosion paint composition makes it possible to obtain a thixotropic effect upon application of the paint to vertical surfaces, which results in a more uniform distribution of particles with a charge of the same sign throughout the paint composition. Distribution ensures their rebound. In this way, a sodium nitrate content below 0.1 part by weight does not provide the effect of a uniform distribution of particles and thus prevents dripping of the starting composition when the composition is applied to vertical surfaces. Can not. A sodium nitrate content above 0.5 parts by weight increases the water solubility of the inclusion and thus impairs its protective properties.

If the application of the coating is carried out by jet casting in mechanized equipment, the sulfanol may be added in an amount of 0.1 to 4.
and 1.5 parts by weight of the organopolysiloxane.
It is recommended to incorporate it into the coating composition in an amount of ~10.0 parts by weight.

Organosiloxanes include polymethylsiloxane, polyethylsiloxane, polyphenylmethylsiloxane,
Polyphenylethoxysiloxane is preferably used. The incorporation of sulfanol into the composition is required to stabilize the dispersion of corrosion-resistant coating compositions, but this can destroy the orientation of the dispersed phase particles when applied in mechanized equipment. This is because it will be done.

A sulfanol content below 0.1 parts by weight does not guarantee the formation of a stable dispersion, while 4. A sulfanol content above 2 parts by weight increases the water solubility of the final film and reduces its protective effect.

The role of the polyorganosiloxane in the starting composition according to the invention consists in the defoaming of the final mixture upon application onto the metal surface, the foaming being caused by the formation of the composition in the presence of an increased amount of surfactant. resulting in fast recirculation.

At polyorganosiloxane contents below 1.5 parts by weight, no defoaming effect is observed, while at organopolysiloxane contents above 1 part by weight the adhesion of the coating to metal surfaces is reduced. be done.

The anticorrosive coatings made according to the invention are distinguished from common paint coating systems by a longer service life, heat resistance, higher resistance to light, oil and gasoline.

Compared to phosphate-based protective coatings, the coating according to the invention is characterized by its heat treatment temperature which is substantially lower. The use of the composition according to the invention results in a low number of coatings (4
(2 times instead of once) reduces labor consumption of painting,
By using water instead of volatile, toxic and hazardous solvents it is possible to ensure dust-proof and fire-proof working conditions and provide better regulation of environmental protection. The effects of the coating according to the invention are therefore obtained in reduced labor and material consumption, lower raw material costs and higher resistance of the resulting coating and a longer service life. The method for producing the paint is simple and preferably carried out as follows.

Aluminum is dissolved in a 70% aqueous orthophosphoric acid solution by heating.

Calcium oxide is then added in small proportions to the solution and heated to a temperature of up to 85° C. until completely dissolved. A calculated amount of chromic anhydride was added to the clear solution thus prepared, stirred until completely dissolved, and cooled to a temperature of 500 mm, and the hexavalent chromium was partially reduced to trivalent chromium. For this purpose, a 36.7% aqueous formalin solution is added.
The solution is 95~. Heat at a temperature of 0 for 20-25 minutes and cool.

Sodium nitrate is added to the solution thus obtained together with the aqueous polymer dispersion, pigment and water, the whole being mixed in such a way as to obtain a homogeneous product.

After checking the viscosity of the body, the composition is applied to the metal surface by grinding, brushing, dipping or casting and dried for IQ minutes at a temperature of 150°C. After cooling the article to a temperature of 30.degree. C., a second layer of the paint is applied and drying is carried out at a temperature of 150.degree. C. for 45 minutes. For a better understanding of the invention, some specific examples are set forth below for illustrative purposes.

Example 1 The ratio P04 (containing therein 6.5 parts by weight of P205)
100%) to 9.4 parts by weight of calcium hydroxide 0. parts by weight were added under heating and uniform molding and completely dissolved.

After the dissolution was complete, 1.2 parts by weight of aluminum hydroxide containing 0.42 parts by weight of aluminum ions were added to the solution and brought to complete dissolution. The resulting clear solution was cooled to room temperature and then chromic anhydride containing 1.45 parts by weight of carbon was added. Total parts by weight were added and the reaction was stirred until its complete dissolution. A 36.7% formalin aqueous solution was added to the resulting orange solution under condensation until the Q203 content in the solution became 0.7 parts by weight, but this amount was 0. .52
It corresponded to parts by weight.

The content of Cr203 in the solution was controlled analytically. To the cooled solution was added 0.1 parts by weight of sodium nitrate, 25 parts by weight of an aqueous dispersion of polymethyl methacrylate and 9 parts by weight of aluminum powder, mixed to a uniform consistency and 2 parts by weight of water were added. .

In the case of mechanized coating of paint by jet casting method,
To the coating composition was added 0.1 part by weight of sulfanol and 1 part by weight of polymethylsiloxane. The composition was applied to metal surfaces by a jet-shot process using mechanized equipment.

Drying of the first coating layer was carried out for 10 minutes at a temperature of 150±5°C. After cooling the article to room temperature of 30° C., a second coating layer was applied and the coating strength thus obtained was heat treated at 150±5° C. for 45 minutes. Example 2P2
Q6. Day 3P04 (100%) containing parts by weight of turtle9.
0.74 parts by weight of calcium hydroxide containing 0.3 parts by weight of calcium ions were added to 5 parts by weight under heating and uniform grading and brought about complete dissolution.

After complete dissolution of Ca(OH)2, the mixture was added with 0.72 parts by weight of aluminum hydroxide containing 0.25 parts by weight of hairluminium ions and heated until complete dissolution. The resulting clear solution was cooled to room temperature and 1.92 parts by weight of chromic anhydride containing 0.90 parts by weight of Cr+6 ions were added and stirred until complete dissolution. 3 for the reduction of Cr into the resulting orange solution.
A 6.7% aqueous formalin solution was added at a ratio of 4. The Cr203 content in the solution upon completion of this step is 0. It should be $ parts by weight, which is 0.64 of C
Corresponds to parts by weight. NaN03 into this cooled solution
0.15 parts by weight, 22 parts by weight of polyepoxidized methyl methacrylate dispersion and 9 parts by weight of zinc powder, the mixture was stirred to homogeneous conditions, 32 parts by weight of water was added, and it was air-blown. Applied to metal surfaces by grinding, dipping or brushing.

Drying the first coating layer at a temperature of 150±5°C for 1 minute,
and the second layer was dried for 45 minutes at the same temperature. Example
3-18 Anticorrosive coating compositions according to these examples are shown in the table below.

The pyridine-containing latexes in the table are Ptadiene-2 and 2-
It is a butadiene-methyl-pinylpyridine latex based on a copolymer of methyl-5-vinylpyridine.

Moreover, polyurethane latex is produced based on a hydrazine derivative of the formula.

quantity words Bamboo, day of the week mulberry sword Go Vertical sadness crab

Claims (1)

[Scope of Claims] 1. A corrosion-inhibiting paint composition containing a phosphate binder, an aqueous solution of bioorthophosphate in which ions of calcium, aluminum, trivalent chromium, and hexavalent chromium are present; a pigment, a polymer organic an aqueous dispersion of the compound, consisting of sodium nitrate and water; those components in parts by weight, phosphate ion (as P_2O_5) 6.5-7
．． 9 Calcium ion 0.36-0.7 Aluminum ion 0.25-0.426 Hexavalent chromium ion 0.9
5-1.45 Trivalent chromium ion 0.52-0.70 Pigment 9.0-25.0 Aqueous dispersion of polymeric organic compound 1.75-28.0 (
A corrosion-inhibiting coating composition characterized in that sodium nitrate (on a dry matter basis) is present in a ratio of 0.1 to 0.5 water (including water in the aqueous dispersion) 23.25 to 57.0. 2. In the composition according to claim 1, the pigments include zinc, aluminum, iron oxide, titanium dioxide,
A corrosion-inhibiting coating composition characterized in that zirconium dioxide or talc is used. 3. In the composition according to claim 1, the aqueous polymeric organic compound dispersion includes polymethyl methacrylate, polyepoxidized methyl methacrylate, poly(butadiene-styrene), polybutadiene carboxylate, and a copolymer of butadiene and methacrylic acid. , polyvinylidene chloride, polyvinyl acetate, pyridine-containing latex, epoxidized polyvinyl acetate, polystyrene carboxylate, polyurethane, polysilicon acrylate,
A corrosion-inhibiting coating composition characterized in that polydivinylstyrene is used. 4. Aqueous solution of bio-orthophosphate in which ions of calcium, aluminum, trivalent chromium, and hexavalent chromium are present in a corrosion-inhibiting coating composition containing a phosphate binder; an aqueous dispersion of pigments and high-molecular organic compounds; , sodium nitrate and water; those components in parts by weight contain phosphate ions (as P_2O_5) 6.5-7
．． 9 Calcium ion 0.36-0.7 Aluminum ion 0.25-0.426 Hexavalent chromium ion 0.9
5-1.45 Trivalent chromium ion 0.52-0.70 Pigment 9.0-25.0 Aqueous dispersion of polymeric organic compound 1.75-28.0 (
(on a dry matter basis) Sodium nitrate is present in a ratio of 0.1 to 0.5 water (including water in the aqueous dispersion) 23.25 to 57.0, and further contains 0.1 to 4 parts by weight of sulfanol and Corrosion-inhibiting coating composition, characterized in that from 1.5 to 10 parts by weight of organosiloxane are additionally present. 5. In the composition according to claim 4, the polyorganosiloxane may include polymethylsiloxane, polyethylsiloxane, polyphenylmethylsiloxane,
A corrosion-inhibiting coating composition characterized in that polyphenylethoxysiloxane is used.