JPS608063B2 - Anticorrosive coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to anticorrosive coating compositions for protecting metal surfaces, particularly ferrous metal surfaces.

Zinc-rich paint, which has been generally known as a corrosion-resistant coating composition, is a paint containing a large amount of metallic zinc powder in a color vehicle, and when applied to the surface of metal, especially steel, its electrochemical Through its action, it exhibits an anticorrosion effect.

Such zinc-rich tints include (a) those using an organic color vehicle as the auburn color agent, (b) those using poppy or an acid ester vehicle, and (c) those using an alkali metal poppy or an acid ester vehicle. and so on. Medium A uses epoxy resin or polyester resin as a color vehicle, and has excellent adhesion to metals and workability, but is inferior to those using inorganic color vehicles in terms of corrosion resistance and durability. , cannot be used without maintenance. Furthermore, during welding, the color vehicle decomposes thermally and generates gas, which tends to cause coating defects. B uses a silicate ester such as ethyl silicate as a bronze coloring agent, so the surface treatment does not need to be as strict as when using an alkali metal silicate, and it is easy to work because it can be made into a one-component type. However, since the paint film is soft, it is easily scratched, and since alcohol is used as a solvent, there is a risk of fire or poisoning during the painting process. c poppy, lithium oxide, poppy,
It uses an aqueous solution of potassium acid, poppy seed, sodium acid, etc. as a bronze coloring agent, and can create a film with excellent corrosion resistance and high hardness, but it requires top-quality surface treatment, and There are problems such as peeling of the top coat due to the elution of the paint and difficulty in imparting water resistance to the paint film. In this case, the methods of imparting water resistance include two methods: a method in which the surface of the coating film is treated after application to elute the alkali to form a water-insoluble silica polymer, and a method in which a water resistance imparting agent (curing There is a method in which a silica polymer film is formed by mixing a silica polymer and drying it. The purpose of the present invention is to improve the drawbacks of the conventional anti-corrosion coating compositions mentioned above, by forming a film with good water resistance by curing at room temperature, and having good adhesion to the base and top coat (organic type). The purpose of the present invention is to provide a zinc-rich vent with good corrosion resistance and excellent corrosion resistance. That is, the present invention is an anticorrosion coating composition comprising an alkali metal reninate, a metal zinc powder, a fired phosphoric acid-silica product, and water.

Hereinafter, the anticorrosive coating composition of the present invention (hereinafter referred to as the present composition)
I will explain the details.

Examples of the alkali metal salts and acid salts to be blended as a coating film-forming component of the present composition include aqueous solutions of sodium salts, potassium salts, and lithium salts, and mixtures thereof.

A small amount of curing agent with a high molar ratio of Si02/R20 (R: alkali metal) can produce a coating film with good water resistance and good adhesion to the top coat. As a commercially available product, S
i○2no Na20 molar ratio 2.0-3.5, Si02/K
20 molar ratio 3.0 to 4.0, Si02/Li20 molar ratio 3.0 to 4.0, and aqueous solution concentration 20 to 4 t. % are available. An aqueous solution containing silica sol can also be used, but the adhesion will be somewhat reduced. When the aqueous solution concentration is low, the strength of the coating film decreases, and when it is high, the viscosity increases and the amount of zinc powder that can be filled is reduced. From this point of view, the blending ratio of the alkali metal poppy and acid salt in the present composition (based on the water-containing composition at the time of preparation; the same applies hereinafter) is 3 to 2% by weight, preferably 3 to 1% by weight, and the blending ratio of water is 3 to 2% by weight. (Including water derived from alkali metal poppy, when an aqueous salt solution is used) is preferably in the range of 10 to 5% by weight, preferably 10 to 2% by weight. It has also been found that lithium silicate is the most effective alkali metal salt. Further, the metal zinc powder to be blended into the present composition may be one for use in paints. The blending ratio is preferably in the range of 40 to 85% by weight, preferably 65 to 85% by weight, in order to effectively exhibit the anticorrosion effect. The feature of this composition is that a phosphoric acid-silica fired product is blended as an alkali metal ash, an acid hardening agent, and/or a water resistance imparting agent.

This phosphoric acid-silica fired product acts as a hardening agent and/or water resistance imparting agent to generate a water-insoluble silica polymer by reacting with alkali metal salts and acid salts, and also acts synergistically with metal zinc powder. It was found that the anti-corrosion effect was excellent.

Phosphoric acid-silica fired product is a mineral whose main component is silica (
Silica mineral (hereinafter referred to as silica mineral) and phosphoric acid are calcined at high temperatures.

Examples of silica minerals include silica gel, silica,
Examples include natural or synthetic minerals such as silica, and those with a relatively large surface area such as silica gel are particularly preferred.

Silica mineral is used in the form of fine particles or powder. Further, the phosphoric acid may be orthophosphoric acid, phosphoric acid anhydride diluted with water, or commercially available phosphoric acid, preferably having a phosphoric acid concentration of about 70 to 90%. Furthermore, phosphoric acid added to this composition
It has been found that even if the phosphoric acid content of the fired silica products is the same, the curing time of the composition can be adjusted by changing the elution rate of the phosphoric acid.

In order to reduce the elution rate of phosphoric acid in the phosphoric acid-silica fired product, for example, use silica gel, which has a large surface area as a silica mineral, and increase the firing temperature to 500 qo or more, or increase the firing temperature to 700 to 100,000 qo or more after crushing the fired product. Just re-fire it.

Even if the total elution amount of phosphoric acid in the phosphoric acid-silica fired product prepared by this method is the same, the elution rate of phosphoric acid is low, so even if the P205/SI02 ratio is increased, the curing of the composition is Water resistance can be significantly improved without promoting water resistance. According to experiments, temperature 25oo, pHIO
．． The amount of phosphoric acid eluted in the aqueous medium of PSO. 007H+0.005, and the temperature is 80°C and pHIO. A phosphoric acid-silica fired product having a total phosphoric acid yield of 0.200 g or more per 1 g of fired product in the aqueous medium of No. 5 is particularly desirable.

The amount of phosphoric acid-silica fired product used in this composition is 1 to 1.
A range of 1 and t% is suitable. The present composition can be prepared by blending the above-mentioned materials in a predetermined ratio and mixing them uniformly.

That is, alkali metal poppy, acid salt 3-2% by weight, preferably 3-1% by weight, metal zinc powder 40-85% by weight, preferably 65-85% by weight, phosphoric acid silica calcined product 1-1. % by weight and 10 to 5% by weight of water, preferably 10 to 2% by weight, and mix in a suitable mixer.
All you have to do is to mix the wafers evenly. Note that if the metal zinc powder and the phosphoric acid-silica fired product are mixed in advance, the hygroscopicity of the phosphoric acid-silica fired product can be reduced and its storage stability can be improved. To use this composition, scale is removed from the surface of the metal material to be coated with shotplast or gritplast, and then this composition is applied to the surface of the metal material by spraying, brushing, roll coater, etc. do it.

Curing varies depending on the concentration of the alkali metal silicate aqueous solution, the type of phosphoric acid-silica fired product, and the amount added.
Elution into water is no longer observed in 2 hours, and curing is completed in 1 to 3 days. This composition possesses the properties of the alkali metal and acid salt systems mentioned above, and in addition, has significantly better anticorrosion performance, good adhesion of the top coat, and can cure at room temperature to provide a coating with good water resistance. .

Next, the effects of the present invention will be illustrated more specifically by Examples.

Examples Three types of compositions shown below were prepared and used for trials along with commercially available products.

This composition m poppy/sodium acid aqueous solution 10 parts by weight (
JIS No. 3 product / Sj02/Na20 molar ratio 3.2) Metallic zinc powder 34 parts by weight Phosphoric acid-silica calcined product 15 parts by weight Water
1 part by weight of the above materials are blended,
This composition '1- was prepared by uniformly mixing the mixture.

The phosphoric acid-silica fired product used for the legs of this composition [1] was prepared according to the following formulation.

85 parts by weight of silica gel type A 10 with a particle size of 300 μm or less
Add 195 parts by weight of % phosphoric acid aqueous solution and heat to 200-250°C.
After drying with
It was crushed to a size smaller than 100 ml, and then fired at 1000 qo for 3 hours.
The amount of phosphoric acid eluted from this fired product was as follows. 2To
pHIO. 5 in water 1 hour later 0.005
Amount of phosphoric acid eluted after 2 hours 0.013 (g
/g-fired product) 3 hours later 0.02580pm o
pHIO. Total phosphoric acid elution amount in water of No. 5 (g/g baked product) 0.688 Composition '21 Poppy,
Poppy seeds, potassium acid (Si02/K
This composition (2) was prepared in the same manner as this composition '11 except that 20 molar ratio 3.6) was used.

This composition [3} Instead of sodium silicate, poppy seeds, lithium oxide (Si02
/Li20 molar ratio 4.1) was used.
In addition to preparing the present composition '3} in the same manner as in }, a commercially available alkali metal poppy and acid salt-based product was prepared as Comparative Example 1}, and a commercially available ethyl sulfate-based product was prepared as Comparative Example 2.

The compositions of the present composition m to [3- and Comparative Examples {1}, '2} were applied to a thickness of about 100 m on a hybrid-blasted steel plate, and various tests were conducted.

The test results are shown in Table 1. Furthermore, various similar tests were carried out by applying an epoxy paint to a thickness of about 100 mm as a top coat. The test results are shown in Table 2. Ship [Ship N Guan Yuryu Haramida Raiden 9 Feng Mizo Military Raiden Gyoku Arashi Oath Poetry Muden Dust Snow'

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Composition '3} is slightly inferior to Comparative Example '1 in impact resistance, but is rather superior in adhesion and anti-corrosion properties.
A comparison with Comparative Example '2) shows that the hardness is much higher. When a top coat is applied, as shown in Table 2, the adhesion is significantly improved compared to the comparative example.

Claims (1)

[Claims] 1. An anticorrosion coating composition comprising 3 to 20% by weight of alkali metal silicate, 40 to 85% by weight of metal zinc powder, 1 to 10% by weight of phosphoric acid-silica calcined product, and 10 to 50% by weight of water.