JPH05339004A - White rust-preventive pigment and its production - Google Patents

Abstract

PURPOSE:To produce a white rust-preventive pigment which is pollution-free and low in toxicity, having an excellent rust preventive power and consisting of zinc calcium phosphite. CONSTITUTION:This white rust-preventive pigment contains the crystalline zinc calcium phosphite with the lattice distance [d(A)] by the powder X-ray diffraction pattern and diffraction intensity (I/I1) shown by the following relation as the effective component. Namely, 6.70:VS, 5,27:W, 4.07:W, 3.70:S, 3.37:S, 3.16:S, 3.06:S, 3.02:M, 2.79:W, 2.70:W, 2.53:M and 2.39:W, where VS is very strong, S is strong, M is medium, and W is a weak diffraction intensity. The pigment is produced by allowing an aq. soln. of calcium biphosphite to react with a zinc compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pollution-free white rust preventive pigment used for preventing metal corrosion and a method for producing the same. Furthermore, it relates to a white rust preventive pigment containing zinc calcium phosphite having a specific crystal structure as an active ingredient, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, rust preventive pigments are lead salts such as lead tin, cyanamide lead and calcium leadate, chromate salts such as basic zinc potassium chromate, tetrabasic zinc chromate and strontium chromate. Have been mainly used.

However, although these rust preventive pigments have excellent rust preventive properties against metals, their use is gradually restricted due to environmental problems in recent years from the viewpoint of toxicity. Therefore, as a so-called pollution-free rust preventive pigment that replaces these, metal phosphates such as zinc phosphate and calcium magnesium phosphate, condensed phosphates such as aluminum tripolyphosphate, zinc phosphite, calcium phosphite, and phosphorus phosphide. A non-polluting and non-toxic rust preventive pigment such as phosphite such as aluminum acid salt, zinc molybdate, etc. has been developed and put into practical use. However, none of these rust-proofing pigments called pollution-free type has a rust-proofing power comparable to that of chromate-based pigments.

However, recently, an improved phosphite-based rust preventive pigment has been proposed as having excellent rust preventive power. For example, JP-A-50-50297 describes a basic zinc phosphite, and JP
58-194725 discloses a zinc hydroxyphosphite complex. Further, JP-A-55-185027 discloses a reaction product of zinc phosphite and zinc white.
No. 16 and JP-A No. 232676/1983 disclose zinc potassium phosphite-based rust preventive pigments. Recently, JP-A-3-111457 discloses a zinc calcium phosphite-based rust preventive pigment, and JP-A-3-285808 discloses a plate-like calcium phosphite-based rust preventive pigment.

[0005]

[Problems to be Solved by the Invention]
The zinc calcium phosphite described in Japanese Patent No. 1457 is produced by mechanochemically reacting phosphorous acid with a mixed slurry system of a zinc compound and a calcium compound, and the reactivity with phosphorous acid in the mixed slurry. Is different between a calcium compound and a zinc compound, and a mechanochemical reaction tends to result in an inhomogeneous product, and only a certain limited composition and physical properties can be obtained.

The present inventors have found that the solubility of calcium phosphite becomes very large in the presence of excess phosphorous acid, and that acidic calcium phosphite is soluble in water. It has been confirmed that the zinc phosphite calcium phosphite having a specific crystalline property obtained by the reaction shows excellent rust preventive power in addition to no pollution and low toxicity.

The present invention was developed based on the above-mentioned matters to be clarified, and provides a white rust preventive pigment made of zinc calcium phosphite which is pollution-free, has low toxicity and excellent rust preventive power, and a method for producing the same. Has a purpose.

[0008]

The white rust-preventive pigment according to the present invention for achieving the above object has a surface spacing [d (A)] and a diffraction intensity (I / I ₁ ) according to a powder X-ray diffraction pattern. The constitutional feature is that crystalline zinc calcium phosphite having the relationship shown in Table 1 below is used as an active ingredient. However, VS in Table 1
Is the strongest, S is the strongest, M is the strongest, and W is the weakest diffraction line intensity.

[0009]

[Table 1]

The white rust preventive pigment according to the present invention comprises phosphorous acid 1
It is characterized in that the powder X-ray diffraction pattern of the composition obtained by setting the total amount of zinc and calcium to 1 mol to 1 mol and arbitrarily changing the ratio of zinc to calcium and keeping the reaction conditions constant shows the above relationship. Attached.

As for the composition, the diffraction pattern with the strongest crystallinity was obtained when the zinc ratio was around 66.7%.
0.67, Ca0.33, shows the chemical composition is estimated to PHO _3. Therefore, as the amount of calcium increases, the X-ray diffraction pattern of calcium phosphite comes to be recognized, and conversely, when the amount of zinc increases, the crystallinity decreases and it is considered that amorphous zinc phosphite is produced. To be disregarded. As the rust preventive power, a fine crystalline white powder having the above diffraction pattern is preferable.

In the zinc calcium phosphite of the present invention, a part of phosphite is replaced with an organic phosphonic acid having a chelating ability, which is a preferable rust preventive pigment having improved rust preventive power. Typical examples of the organic phosphonic acid include aminoalkylenephosphonic acid, ethylenediaminetetraalkylenephosphonic acid, alkylmethane-1-hydroxy-1,1-diphosphonic acid, and 2-hydroxyphosphonoacetic acid.

Among these, as the aminoalkylenephosphonic acid, for example, nitrilotrismethylenephosphonic acid, nitrilotristrisethylenephosphonic acid, nitrilotristrispropylenephosphonic acid, nitrilodiethylmethylenephosphonic acid, nitrilopropylbismethylenephosphonic acid and the like are ethylenediaminetetraalkylenephosphonic acid. As an acid,
For example, ethylenediaminetetramethylenephosphonic acid, ethylenediaminetetraethylenephosphonic acid, ethylenediaminetetrapropylenephosphonic acid and the like, and as alkylmethane-1-hydroxy-1,1-diphosphonic acid, for example, methane-1-hydroxy-1,1-diphosphonic acid. Acid, ethane-1-hydroxy-1,1-diphosphonic acid, propane-1-hydroxy-1,1-diphosphonic acid and the like can be mentioned, and they may be one kind or two or more kinds.

The content of the organic phosphonic acid having a chelating ability with respect to zinc calcium phosphite varies depending on the type of the compound and the method for preparing the pigment described later, but is generally 20% of the amount of phosphorous acid. A substitution amount within the range is sufficient.
Even if it is more than this, there is little hope of increasing the effect and it will be uneconomical. The white rust preventive pigment according to the present invention is, in order to improve the dispersibility, surface-treated with a higher fatty acid or a derivative thereof, a surfactant, an acidic phosphoric acid alkyl ester or a metal salt thereof as necessary. It may be.

The white rust-preventive pigment of the present invention having the above-mentioned crystallinity can be industrially advantageously produced by reacting an acidic calcium phosphite aqueous solution with a zinc compound.

The raw material acidic calcium phosphite aqueous solution is
It is prepared by dissolving calcium phosphite powder in phosphorous acid. Although calcium phosphite is a white powder, it has high solubility in phosphorous acid, and when 1 mol or more of phosphorous acid is added to 1 mol of the calcium salt, it is solubilized and becomes an acidic calcium phosphite aqueous solution. Examples of the zinc compound to be reacted with the acidic calcium phosphite aqueous solution include zinc oxide (zinc white), zinc hydroxide, zinc carbonate, basic zinc carbonate and the like, and they are used as a slurry. In this case, it is preferable to use a homogenizer, a colloid mill, a ball mill, or the like in advance for strong shear cutting to use as a finely divided slurry.

As a mode of reacting the above-mentioned acidic phosphite aqueous solution with a suspension of a zinc compound dispersed in water, the suspension of the zinc compound dispersed in water is agitated while stirring. Method of adding aqueous solution of calcium phosphate, method of simultaneously preparing suspension of zinc compound dispersed in water and aqueous solution of acidic calcium phosphite, suspension of zinc compound dispersed in water while stirring aqueous solution of acidic calcium phosphite Means such as a method of adding

In the above reaction, an organic phosphonic acid having a chelating ability can be present. The method of adding the organic phosphonic acid includes, for example, a method of adding the zinc compound at the time of slurrying, a method of adding during the solubilization of calcium phosphite, or a method of adding in the course of the above reaction. There is no particular limitation. The organic phosphonic acid can be used as an aqueous solution of an alkali metal salt or an ammonium salt in addition to the above-mentioned phosphonic acid.

By this reaction, white fine crystals of zinc calcium phosphite are deposited, and after the reaction is completed, solid-liquid dispersion and, if necessary, washing with water, separation are carried out, followed by drying and pulverizing by a conventional method to obtain a product. The surface treatment for the purpose of improving dispersibility can be performed as a post-treatment after completion of the reaction.

The zinc phosphite alkali metal salt and the phosphite alkali metal salt composition produced in the above steps are used as an anticorrosive pigment composition by dispersing them in an oily or aqueous vehicle used for ordinary paints. To be done. In addition, zinc phosphate, basic zinc phosphite, condensed aluminum phosphate,
It can also be used in combination with a rust preventive pigment such as a metal salt of molybdic acid.

[0021]

The white rust-preventive pigment according to the present invention contains zinc calcium phosphite as a main component, which has the crystallographic properties such as the interplanar spacing and diffraction intensity according to the powder X-ray diffraction pattern as shown in Table 1. The crystal properties are non-polluting and have low toxicity, and also function to exert excellent rust prevention.

The white rust preventive pigment having such characteristics can be efficiently produced by the production method of the present invention in which the aqueous solution of acidic calcium phosphite and the zinc compound slurry are subjected to solid-liquid reaction.
Although the details of this reaction mechanism are unknown, the dissolution of the zinc compound becomes the reaction rate-determining reaction and the neutralization reaction proceeds, and the Zn in the reaction system
It is presumed that specific microcrystalline particles of zinc calcium phosphite are produced by the coprecipitation reaction of ²⁺ and Ca ²⁺ with HPO ₃ ^{2 −} . The obtained white precipitate has the above-mentioned X-ray pattern and exhibits excellent rust preventive power against metals.

[0023]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Example 1 After dispersing 122 parts by weight of zinc oxide in 700 parts by weight of water,
A micronized slurry was prepared by passing through a colloid mill. Meanwhile, 40 parts by weight of phosphorous acid is added to 74 parts by weight of calcium hydroxide.
An aqueous solution of acidic calcium phosphite was prepared by adding 410 parts by weight. Then, an acidic calcium phosphite aqueous solution was added over 30 minutes to the zinc oxide slurry heated to 50 ° C. with stirring. After the addition was completed, stirring was continued for 2 hours while being heated to 50 ° C. The formed precipitate was filtered, dried at a temperature of 110 ° C., and then pulverized to obtain a white powder (Sample 1).

Example 2 244 parts by weight of zinc oxide was dispersed in 1000 parts by weight of water and passed through a colloid mill to prepare a finely-divided slurry. This slurry
After heating to 50 ° C., 410 parts by weight of the same acidic calcium phosphite aqueous solution prepared in Example 1 was added to the slurry while stirring for 1 hour. After the addition was completed, the temperature was maintained at the same temperature and stirring was continued for 2 hours. Then, the precipitate was filtered by a conventional method, dried (115 ° C) and pulverized to obtain a white powder (Sample 2).
Got

Example 3 A white powder (Sample 3) was obtained by the same operations and conditions as in Example 2 except that a finely divided slurry of zinc oxide in which 326 parts by weight of zinc oxide was dispersed in 1200 parts by weight of water was used. It was

Example 4 Example 1 using 600 parts by weight of water and 98 parts by weight of zinc oxide.
A slurry of finely divided zinc oxide was prepared by the same treatment as described above. The slurry was heated to 40 ° C. and stirred, and 33 parts by weight of a 50% by weight nitrilotrimesmethylenephosphonic acid solution was added, and the mixture was kept for 1 hour. The same acidic calcium phosphite aqueous solution used in Example 1 was added to this slurry over 30 minutes, and stirring was continued for about 2 hours while being heated to 40 ° C. The precipitate was then filtered, dried (110 ° C) and ground to give a white powder (Sample 4).

Example 5 The same zinc oxide slurry as in Example 4 was mixed with 50% by weight of ethane.
33 parts by weight of 1-hydroxy-1,1-diphosphonic acid solution was added, and stirring was continued at 40 ° C. for 1 hour. In this slurry,
An acidic calcium phosphite aqueous solution prepared by adding 369 parts by weight of 40% by weight phosphorous acid to 74 parts by weight of calcium hydroxide was added over 1 hour. After the addition was completed, stirring was continued for about 2 hours while being heated to 40 ° C. Then, the precipitate was filtered by a conventional method, dried at 110 ° C., and then pulverized to obtain a white powder (Sample 5).

Comparative Example 1 87 parts by weight of zinc oxide and 100 parts by weight of calcium carbonate were added to 750 parts of water.
A slurry was prepared by dispersing it in parts by weight. While stirring this slurry, 410 parts by weight of 40% by weight phosphorous acid was added over 1 hour, and subsequently wet-milled for 6 hours using a porcelain ball mill. Then, the slurry was filtered, the precipitate was dried at 110 ° C. for 24 hours and then pulverized to obtain a white powder (Sample 6).

(1) Preparation of Anticorrosion Paint Using the white powders obtained in Examples 1 to 5 and Comparative Example 1 and the commercially available antirust pigment, the antirust paint was prepared according to the formulation shown in Table 2. .. In addition, the thing which does not use a rust preventive pigment used zinc oxide instead of the rust preventive pigment.

[0031]

[Table 2] Table Note: (Note 1) "Beckosol 1334" non-volatile content 50%
Middle oil alkyd resin [manufactured by Dainippon Ink and Chemicals, Inc.] (Note 2) Liquid dryer (JIS K5691, Class 1A)

The above-prepared coating material and 100 g of glass beads (GB603, manufactured by Toshiba Glass Co., Ltd.) were placed in a 100 ml mayonnaise bottle and dispersed for 1 hour using a paint shaker to prepare a coating material.

(2) Evaluation of Anticorrosion Ability Each of the above paints was applied to a cold-rolled steel plate [manufactured by Japan Test Panel Industry Co., Ltd., JIS G3141, SPCC-SB, 1.0
X70 × 150 mm) was coated using a bar coder so that the film thickness after drying would be 15 μm. After the coating film was dried at room temperature, a salt spray test with 5% saline without overcoating (manufactured by Suga Test Instruments Co., Ltd., salt spray tester, ST-IS
O-2 was used) to evaluate the rust preventive ability of each pigment. The obtained results are shown in Table 3.

The evaluation of the rust preventive performance was made by observing the condition of the test piece and judging according to the following criteria. Rust occurrence rate of 100% …… 1 Rust occurrence rate of 75% …… 2 Rust occurrence rate of 50% …… 3 Rust occurrence rate of 25% …… 4 Blistering No rust ... 5

[0035]

[Table 3]

[0036]

INDUSTRIAL APPLICABILITY As described above, the white rust preventive pigment according to the present invention has excellent corrosion resistance and rust preventive property as compared with the conventional white rust preventive pigments. In addition, since the active ingredient is composed of zinc calcium phosphite that is not a chromate type or lead salt type, it is a low-pollution, non-polluting white rust-preventive pigment that can be used in food-related and anti-rust paints for toys. it can. Further, according to the production method of the present invention, such a white rust preventive pigment can be industrially advantageously produced through a simple reaction step.

Claims (4)

[Claims] 1. A white rust-preventive pigment comprising crystalline calcium zinc phosphite as an active ingredient, which shows the following relationship between the interplanar spacing and the diffraction intensity according to the powder X-ray diffraction pattern. Surface spacing [d (A)] Diffraction intensity (I / I ₁ ) 6.70 VS 5.27 W 4.07 W 3.70 S 3.37 S 3.16 S 3.06 S 3.02 M 2. 79 W 2.70 W 2.53 M 2.39 W where VS is the strongest, S is the strongest, M is the medium strong and W is the weak diffraction line intensity. 2. The white rust preventive pigment according to claim 1, wherein the zinc calcium phosphite is obtained by substituting a part of phosphorous acid with an organic phosphonic acid having a chelating ability. 3. A method for producing a white rust preventive pigment, which comprises reacting an acidic calcium phosphite aqueous solution with a zinc compound. 4. The method for producing a white rust preventive pigment according to claim 3, wherein an organic phosphonic acid having a chelating ability is present in the reaction between the acidic calcium phosphite aqueous solution and the zinc compound.