JP3226064B2 - Rust prevention pigment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust preventive pigment. More specifically, the present invention relates to a rust preventive pigment which is non-polluting and has an excellent rust preventive effect.

[0002]

2. Description of the Related Art Heretofore, chromium pigments such as zinc chromate and strontium chromate, and lead pigments such as lead chromate and cyanamide lead have been mainly used as rust preventive pigments for paints (for example, Tokiko Sho 53
-31495). This is because chromium-based pigments and lead-based pigments have excellent rust preventive action.

[0003]

However, chromium-based rust-preventive pigments and lead-based rust-preventive pigments contain harmful metals such as chromium (hexavalent chromium) and lead, which may impair human health. However, there is a problem with safety, and it has recently been subject to pollution control. Therefore, a rust-preventive pigment that is non-polluting and excellent in rust-preventing effect is demanded.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to meet the above demands using iron dihydrogen tripolyphosphate or its dihydrate, whose industrial process has been previously developed. When they are used in combination with zinc oxide, they have found that a rust preventive pigment having no pollution and excellent rust preventive effect can be obtained, and the present invention has been completed.

That is, the present invention relates to a specific manufacturing method described later.
The present invention relates to a rust preventive pigment comprising a mixture of iron dihydrogen tripolyphosphate or its dihydrate and zinc oxide produced by the method in a weight ratio of 10/1 to 10/10 .

In the rust preventive pigment of the present invention, iron dihydrogen tripolyphosphate used as a component thereof has a descriptive formula of FeH ₂ P ₃ O ₁₀ and has properties as a solid acid.
The crystal was measured by powder X-ray diffraction to obtain 2θ =
It has a very large peak around 11.1 ° and has a layered structure.

[0007] The above-mentioned iron dihydrogen tripolyphosphate and its dihydrate are hardly soluble in water and are not easily eluted in water, but slightly dissolved in water under a corrosive atmosphere. Occasionally, it releases tripolyphosphate ions that exhibit an excellent rust-preventive action against iron corrosion.

However, the above-mentioned iron dihydrogen tripolyphosphate and its dihydrate are substances which show an acidity as a kind of solid acid, so that the coating film is turned to an acidic side as it is, and the rust-preventive action of the tripolyphosphate ion is prevented. Does not work effectively.

Therefore, in the present invention, this diiron dihydrogen triphosphate or a dihydrate thereof acting as a solid acid,
By using the solid base in combination with zinc oxide, the coating film was kept neutral, the rust-preventing action of tripolyphosphate ions was effectively exerted, and an excellent rust-preventing effect was obtained.

When tripolyphosphate ions are excessively eluted from iron dihydrogen tripolyphosphate or its dihydrate,
The coating may swell (bulge) and reduce the rust prevention effect. However, when zinc oxide is used in combination, excess tripolyphosphate ions are fixed by the zinc oxide, preventing the coating from swelling. Therefore, the rust prevention effect can be efficiently exhibited.

It is necessary to use the above-mentioned iron dihydrogen tripolyphosphate and its dihydrate produced by the method developed by the present inventors first and applied for a patent (Japanese Patent Application No. 5-100493). is there.

The production method developed by the present inventors will be described. This is a method for producing iron dihydrogen tripolyphosphate through the following steps (1) to (4).

A phosphoric acid compound and an iron oxide are blended at a molar ratio of phosphorus to iron of P / Fe of 2.0 to 3.5,
Reaction process of heating at 100-150 ° C

[0014] The reaction solution obtained above is used for 100 to 1
Step of heating at 80 ° C. to form ferrous iron phosphate crystals

A step of firing the ferrous ferrous phosphate crystals obtained above at 200 to 300 ° C. in a steam atmosphere to obtain iron dihydrogen tripolyphosphate.

The iron dihydrogen tripolyphosphate obtained through the above-mentioned steps is an anhydrous type which does not retain water of crystallization, and has a very strong ability to take in water of crystallization. Although it is possible to use an anhydride, industrially, it is preferable to use it in the form of a dihydrate containing water of crystallization because it is easier to handle.

The dihydrate of iron dihydrogen tripolyphosphate is hydrolyzed by throwing the mass after the above-mentioned calcination step into a large amount of water or hot water, and the resulting slurry is filtered, dried and crushed. Obtained by: By this water addition step, the lump is broken down into crystalline fine particles, and the water-soluble components present in the lump can be removed.

The iron dihydrogen tripolyphosphate and its dihydrate obtained as described above have high purity and are obtained in the form of fine powder, so that the layered crystal structure is not destroyed by the pulverization.
Since it exhibits an excellent rust preventive action, it is suitable as iron dihydrogen tripolyphosphate or its dihydrate used as a component of the rust preventive pigment of the present invention.

[0019]

In the rust-preventive pigment of the present invention, zinc oxide, which is the other component, does not require a special one, and those generally used for industrial purposes can be used. This zinc oxide acts as a dryer (desiccant) for alkyd resins to accelerate the drying of the coating film, and by making the coating film more dense, it prevents the permeation of water and oxygen, which are factors of corrosion, Itself exhibits alkalinity and has a rust-preventing action such as delaying the progress of corrosion of the article to be coated by keeping the surface of the article alkaline, but the action alone is small, and as described above, tripolyphosphate When used in combination with iron hydrogen or its dihydrate, a large rust-preventing effect that cannot be obtained when each is used alone is obtained.

The mixing ratio of iron dihydrogen tripolyphosphate or its dihydrate to zinc oxide is 10/1 to 10 by weight.
/ 10.

That is, when the mixing ratio of iron dihydrogen tripolyphosphate or its dihydrate is less than the above range,
The amount of generation of tripolyphosphate ion, which is a factor exhibiting the rust preventive action, is reduced, the rust preventive action is not sufficiently exhibited, and the mixing ratio of dihydrogen tripolyphosphate or its dihydrate is more than the above range. Then, the decrease in zinc oxide makes it impossible to neutralize the solid acidity of the iron dihydrogen tripolyphosphate or its dihydrate, so the rust-preventive action based on the iron dihydrogen tripolyphosphate or its dihydrate Is not sufficiently exhibited, and blisters appear in the coating film.

[0023]

The rust preventive pigment of the present invention is obtained by using the above specific tripolyiron dihydrogen phosphate or its dihydrate in combination with zinc oxide. Can be performed by either dry mixing or wet mixing. In particular, when it is necessary to disperse the rust-preventive pigment in a resin having poor stability in forming a coating, it is preferable that these components are subjected to a wet reaction in advance by a wet mixing method.

The wet reaction can be either a batch type or a continuous type, and the order of mixing the components to be added in the reaction may be any of them. The reaction temperature in the wet reaction is suitably in the range from room temperature to 80 ° C., and the reaction time is usually 30 minutes to 3 hours. After the completion of the reaction, the reaction slurry is filtered and dried, and the obtained dried product is pulverized to obtain a target rust preventive pigment.

However, what has been subjected to the wet reaction as described above only reacts to such an extent that a part is different from the original component, and a clear reaction does not always occur. It can be included in the category of a mixture.

In forming the rust preventive pigment of the present invention into a paint, various resins can be used without any particular limitation, for example, boiling oil, oil varnish, phenol resin, amino resin, epoxy resin. , Urethane resin, vinyl resin, acrylic resin, fluorine resin, silicone resin, synthetic resin for various coatings such as polyester resin, rubber derivatives such as chlorinated rubber and cyclized rubber, and other fiber derivatives alone or in combination. Can be used.

When the rust preventive pigment of the present invention is dispersed in a paint resin, the iron dihydrogen tripolyphosphate or its dihydrate and zinc oxide are separately mixed without previously mixing them. May be added therein so that they are mixed in the resin.

[0029]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples. Prior to the examples, a production example of iron dihydrogen tripolyphosphate dihydrate (dihydrate of iron dihydrogen tripolyphosphate) used in the examples is shown as Reference Example 1.

Reference Example 1 [Production Example of Iron Dihydrogen Tripolyphosphate Dihydrate] 800 g of 85% phosphoric acid (orthophosphoric acid) and α-iron oxyhydroxide (α-FeOOH: Fe ₂ O ₃ as 88. 5
209 g) was placed in a separable flask having an internal volume of 1 liter equipped with a reflux condenser and a stirring blade, and heated under stirring with a mantle heater for about 1 hour.
The temperature was raised to 20 ° C. over 1 hour. The molar ratio of phosphorous to iron of the above phosphoric acid and α-iron oxyhydroxide is P / Fe = 3.0.
Met.

When heating is continued at this temperature for about 150 minutes,
All the α-iron oxyhydroxide was dissolved in phosphoric acid, and the reaction solution became transparent. Thereafter, the reflux condenser was removed from the separable flask, and the temperature was raised to 130 ° C. over about 15 minutes, and the reaction solution thickened as water evaporated.
Finally crystallized.

Next, the crystallized product was taken out of the separable flask, transferred to a crystal dish, and dried at 170 ° C. for 150 minutes to obtain 900 g of ferrous phosphate crystals. The crystals of ferrous iron phosphate have a heat loss at 600 ° C. of 1
It was 5.2% by weight.

The above ferrous iron phosphate crystals were heated at a temperature of 270.
The resultant was calcined by heating it in a steam atmosphere for 20 hours in a steam dryer at 20 ° C., throwing the resulting calcined product into 3 liters of hot water at 80 ° C., and stirring the resulting slurry for about 2 hours.

This slurry was separated by filtration using a Buchner funnel and filter paper, and the obtained dehydrated cake was dried at 90 ° C. for 12 hours, and then pulverized into a fine powder with a crusher to obtain 730 g of powder. Was.

When the powder X-ray diffraction measurement of the obtained final product was performed, the powder X-ray diffraction pattern was 2θ = 11.0.
It had a very large peak around 1 °.

Raw materials used and powder X of the final product
From the diffraction pattern, the final product obtained was found to be iron dihydrogen tripolyphosphate dihydrate (FeH ₂ P ₃ O ₁₀ .2H
₂ O) was found to be the main component.

Example 1 An antirust pigment was prepared by mixing iron dihydrogen tripolyphosphate dihydrate produced in Reference Example 1 and zinc oxide at a weight ratio of 8/3.

Example 2 An anticorrosive pigment was prepared by mixing iron dihydrogen tripolyphosphate dihydrate prepared in Reference Example 1 and zinc oxide at a weight ratio of 10/8.

The rust preventive effect of the rust preventive pigment of Example 1 and the rust preventive pigment of Example 2 obtained as described above was examined with a medium oil alkyd coating film and a water-soluble alkyd coating film. Test Example 1 shows the case of the medium oil alkyd coating film, and Test Example 2 shows the case of the water-soluble alkyd coating film. In each test, for comparison, when iron dihydrogen tripolyphosphate dihydrate was used alone, when zinc oxide was used alone, and when blank (that is, no rust preventive pigment was blended) Case) was also examined for rust prevention effect.

Test Example 1 Middle oil alkyd-based coating film First, a dispersion of a rust-preventive pigment was prepared at the compounding ratio shown in Table 1, and the dispersion was used to make a paint at the compounding ratio shown in Table 2. In each case, the oxidation ratio is based on weight.

The dispersion is prepared by placing each component in a container filled with glass beads and mixing with a paint conditioner for 30 minutes. This was done by placing them inside and mixing with a paint conditioner for 10 minutes.

Types of Rust Preventive Pigment Example 1: Iron dihydrogen tripolyphosphate dihydrate / zinc oxide = 8/3 (weight ratio) Example 2: Iron dihydrogen tripolyphosphate dihydrate / zinc oxide = 10/8 (weight ratio)

The mixing ratio of the rust preventive pigment at the time of preparing the dispersion is as follows:
Example 1 and Example 2 are the same as in the case of iron dihydrogen tripolyphosphate dihydrate alone, and in the case of zinc oxide alone (these are collectively referred to as “other than blank”). Is the same as the blank except for the blank.

[0044]

[Table 1] * 1 Brand name, Dai-Nippon Ink and Chemicals Co., Ltd., 50% solid content alkyd alkyd resin liquid * 2 Kansai Paint Co., Ltd. paint thinner A

[0045]

[Table 2] * 3 Trade name, polyester resin based anti-skinning agent manufactured by Kusumoto Chemicals * 4 Trade name, anti-settling agent manufactured by Kusumoto Chemicals

Coating Conditions Each of the above five types of coating materials was applied on a plate under the following coating conditions, and dried at room temperature for one week to form a coating film.

Coating: Bar coater coating Coated plate: Degreasing treated mild steel plate JIS G 3141 (manufactured by Nippon Test Panel Industries) Film thickness: 30 ± 1 μm

Test conditions A test plate having a coating film formed on a substrate to be coated as described above was cut to reach the substrate to be coated, and a 5% aqueous solution of sodium chloride was placed in a salt spray tester in which the temperature inside the device was maintained at 35 ° C. 1k
g / cm ² was sprayed onto the coating surface of the test plate, and on the 17th day, generation of rust (rust) on the test plate and blistering (bulging) of the coating film were observed.

Test Results The results of the above salt spray test are shown in Table 3 for each type of rust preventive pigment. The rust prevention effect is evaluated by the rust generation prevention effect of the test plate and the blister generation prevention effect of the coating film. The evaluation criteria are as follows.

The evaluation criterion for the rust prevention effect is AS
In accordance with TM D610-68 (1970), the evaluation criteria for the blister generation preventing effect is ASTM D714-59 (1
965).

Therefore, as is clear from the following evaluation criteria, the higher the evaluation value, the better the rust generation preventing effect and the blister generation preventing effect.

Evaluation criteria of rust generation preventing effect 5: Rust generation area: less than 0.1% 4: Rust generation area: 0.1% or more to less than 1% 3: Rust generation area: 1% to less than 10% 2: Rust generation Area 10% or more to less than 33% 1: Rust occurrence area 33% or more

Evaluation criteria for blister prevention effect 5: 8F or less 4: 8M, 6F 3: 8MD, 6M, 4F 2: 8D, 6MD, 4M, 2F 1: 6D, 4MD or more, 2M or more

[0054]

[Table 3]

As shown in Table 3, the rust preventive pigment of Example 1 and the rust preventive pigment of Example 2 in which iron dihydrogen tripolyphosphate dihydrate was used in combination with zinc oxide exhibited an effect of preventing rust generation, Each of the generation preventing effects had a high evaluation value and had an excellent rust preventing effect.

Test Example 2 Water-Soluble Alkyd-Based Coating Compositions shown in Table 4 for the rust preventive pigment of Example 1, the rust preventive pigment of Example 2, iron dihydrogen triphosphate dihydrate, zinc oxide and blank Was prepared as a dispersion, and formed into a coating material in the mixing ratio shown in Table 5. The method for preparing the dispersion and forming the coating is the same as in Test Example 1. The mixing ratio of the rust-preventive pigment at the time of preparing the dispersion is the same as that of Example 1, Example 2, the case of using iron dihydrogen tripolyphosphate dihydrate alone, and the case of using zinc oxide alone. Is the same as the blank except for the blank.

[0057]

[Table 4] * 5 Trade name, titanium oxide (TiO ₂ ) manufactured by Teica * 6 Trade name, water-soluble alkyd resin manufactured by Nippon Shokubai Chemical Co., Ltd.

[0058]

[Table 5] * 7 Trade name, water-soluble dryer (desiccant) manufactured by Dainippon Ink and Chemicals, Inc.

Next, each of the above five types of paints was applied on a plate to be coated, and a salt spray test was performed. Table 6 shows the test results. The coating conditions, test conditions, and the method of evaluating the test results are the same as in Test Example 1.

[0060]

[Table 6]

As shown in Table 6, the rust preventive pigment of Example 1 and the rust preventive pigment of Example 2 using the specific iron dihydrogen tripolyphosphate dihydrate and zinc oxide in combination were used. Has a high evaluation value for both the rust generation prevention effect and the blister generation prevention effect,
It had an excellent rust prevention effect.

[0062]

As described above, the rust preventive pigment of the present invention has no pollution and has an excellent rust preventive effect.

Continuation of the front page (56) References JP-A-3-146567 (JP, A) JP-A-4-359973 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 5 / 08 C09C 1/04 C23F 11/00 WPI (DIALOG)

Claims (1)

(57) [Claims] 1. A rust preventive pigment comprising a mixture of iron dihydrogen tripolyphosphate or a dihydrate thereof and zinc oxide in a weight ratio of 10/1 to 10/10 , wherein said tripolyphosphate dihydrate
The elemental iron converts the phosphate compound and the iron oxide into a molar ratio P between phosphorus and iron.
/ Fe in a ratio of 2.0 to 3.5, and 100 to 15
Reaction step of heating at 0 ° C., heating the reaction solution obtained above at 100 to 180 ° C.
And turning the ferrous phosphate crystals obtained above into a steam atmosphere.
Fired at 200-300 ° C in the air, tripolyphosphate dihydrate
It is manufactured through a process to make
The dihydrate of iron dihydrogen polyphosphate is not
Is poured into a large amount of water or warm water to disintegrate
Filter, dry and disintegrate the resulting slurry.
Thus , a rust-preventive pigment characterized by being obtained .