JP2003113482A - Rust preventive pigment composition for water paint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition of a nonpolluting rust preventive pigment, which does not adversely affect on storage stability of a coating material when blended with a water paint. SOLUTION: The composition of the rust preventive pigment comprises a water-unsoluble reacted product of sodium tripolyphosphate with a water-soluble polyvalent metal salt in an aqueous solution.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rust preventive pigment composition. More specifically, the present invention relates to a rust preventive pigment composition which is non-polluting and has excellent rust preventive ability and does not adversely affect the storage stability of the paint even when it is compounded in an aqueous paint.

[0002]

2. Description of the Related Art Conventionally, as rust preventive pigments, lead-based pigments such as red lead, lead suboxide, cyanamide lead, calcium leadate, basic lead sulfate and basic lead chromate, zinc chromate, strontium chromate, barium. Chromate, calcium chromate and other chromium pigments, zinc phosphate, calcium phosphate, aluminum phosphate, titanium phosphate, phosphite, hypophosphite and other phosphate pigments, zinc molybdate, calcium molybdate, Molybdate pigments such as zinc phosphomolybdate and other borate pigments such as barium metaborate were used.

In recent years, pollution regulations for heavy metal elements such as lead and chromium have been strengthened, and accordingly, the amount of non-polluting phosphate pigments used has greatly increased. In particular, a rust preventive pigment composition containing aluminum trihydrogen phosphate which is a layered phosphate has excellent rust preventive properties, as a pollution-free rust preventive pigment containing no heavy metal, solvent-based, water-based, It is widely used in various coating systems such as powder systems (Japanese Patent Laid-Open No. 55-160059).

Layered phosphates widely used as anticorrosive pigments include, for example, aluminum dihydrogen tripolyphosphate [AlH ₂ P ₃ O ₁₀ .nH ₂ O (n = 0 or 2)],
Titanium phosphate [Ti (HPO ₄ ) ₂ · nH ₂ O (n = 0
Or 2)], zirconium phosphate [Zr (HPO ₄ ).
₂ · nH ₂ O (n = 0 or 2)], cerium phosphate [Ce (HPO ₄ ) ₂ · nH ₂ O (n = 1.33 or 2)] and the like. Particularly dihydrogen tripolyphosphate aluminum, when used as anticorrosive pigment, to elute the tripolyphosphate ions (P ₃ O ₁₀ ^5-) in a corrosive environment, orthophosphate ions eluted from other layered phosphate (PO ₄
Compared to ^3- ), the chelating power for iron ion, which is a component of rust, is very large and it is preferable as a rust preventive pigment.

In addition to the layered phosphate described above, zinc phosphate [Zn ₃ (PO ₄ ) ₂ .nH _{2 is} used as a pollution-free rust preventive pigment.
O (n = 2 or 4)], but the orthophosphate anion (PO ₄ ³⁻ ), which is a component that exhibits anticorrosive properties, is a tripolyphosphate ion (PO ₄ ³⁻ ) which has a chelating power for iron from aluminum tripolyphosphate ( P ₃ O ₁₀ ^5-) for weaker than, sufficient rust preventive effect.

[0006]

It is a social problem today to reduce volatilization of VOCs into the atmosphere for environmental protection. Therefore, the use of water-based paints is increasing in the paint field. Although conventional layered phosphate-based rust preventive pigments, especially aluminum dihydrogen tripolyphosphate, are excellent in rust preventive performance, they have a drawback that they deteriorate the storage stability of the paint when used in water-based paints. Therefore, there is a demand for a pollution-free rust preventive pigment that is equivalent to or more excellent in rust preventive power than the conventional rust preventive pigments and does not adversely affect the storage stability of the paint when used in an aqueous paint.

[0007]

The present invention satisfies the above-mentioned needs by providing a rust preventive pigment composition comprising a poorly water-soluble reaction product of sodium tripolyphosphate and a water-soluble polyvalent metal salt in an aqueous solution.

The present invention also relates to a method for producing the above-mentioned rust preventive pigment composition, which comprises reacting sodium tripolyphosphate with a water-soluble polyvalent metal salt in an aqueous solution and filtering, washing, drying and pulverizing the formed precipitate. Concerned.

The rust preventive pigment composition of the present invention is rather excellent in rust preventive power as compared with the known layered phosphate rust preventive pigments, and makes the storage stability of the paint practically unusable when used in an aqueous paint. Do not lower as much as you can.

[0010]

Preferred Embodiment Sodium tripolyphosphate used in the present invention has the formula Na ₅ P ₃ O ₁₀ , and is used in applications such as sequestering agents, dyeing auxiliaries, water canning agents, synthetic detergent builders and food additives. It is a compound that is easily soluble in water.

The polyvalent metal salt, which is the other raw material, is required that the metal species does not have an unacceptably harmful effect on the environment and that it is soluble in water.

For this purpose, a metal salt composed of one or more metals selected from zinc, aluminum, cerium, iron or alkaline earth metals and one or more salts selected from sulfates, nitrates or chlorides. Among them, if soluble, they can be used, but aluminum, zinc, magnesium, and calcium are particularly preferable as the metal species from the viewpoint of rust prevention performance. Examples of aluminum salts include aluminum sulfate, aluminum chloride, aluminum nitrate and the like.

As described above, metal tripolyphosphate exhibits excellent performance as an anticorrosive pigment for water-based paints, but since it does not exist in nature, it is produced synthetically.

In a conventional general method for producing a metal salt of tripolyphosphate, phosphoric acid (for example, 85%) and a metal compound (for example, for producing an aluminum salt, (water) are used).
Aluminum oxide) is mixed and reacted, dried, calcined and pulverized. The rust preventive pigment of the present invention starts from an aqueous solution of sodium tripolyphosphate and an aqueous solution of a soluble metal salt, and the aqueous solution of sodium tripolyphosphate is treated with a soluble metal salt. It can be obtained by sufficiently washing and drying the precipitate formed by adding and adjusting the pH as necessary.

That is, an aqueous solution of sodium tripolyphosphate and an aqueous solution of a water-soluble aluminum salt such as aluminum sulfate, aluminum chloride or aluminum nitrate, a water-soluble cerium salt, a titanium salt or an alkaline earth metal salt are prepared in advance, and these are prepared. Are mixed at a molar ratio capable of forming a precipitate (M / 3P, M: metal ion, 3P: tripolyphosphate ion), and the precipitate formed is filtered to separate, washed with water, dried, and pulverized. Manufactured by. As a procedure for forming a precipitate, an aqueous solution of a water-soluble metal salt may be added to an aqueous solution of sodium tripolyphosphate, or conversely, an aqueous solution of sodium tripolyphosphate may be added to an aqueous solution of a water-soluble metal salt. 2 more
It is also possible to mix an aqueous solution of more than one type of water-soluble metal salt to obtain a precipitation product in the form of a double salt.

The molar ratio (M / 3P) and the p
H varies depending on the type of water-soluble metal liquid to be combined with the sodium tripolyphosphate aqueous solution, but M / 3P =
Range of 0.5-10, preferably M / 3P = 1-7.5
The molar ratio may be adjusted within the range.

For example, in the case of sodium tripolyphosphate aqueous solution and aluminum chloride aqueous solution, M / 3P = 1 to
It is preferable to obtain a precipitate in the range of 7.5, and the pH of the aqueous solution at that time is in the range of 2.5 to 4.5. Also,
A precipitate may be formed using caustic soda, sulfuric acid, hydrochloric acid or the like while adding the sodium tripolyphosphate aqueous solution and the water-soluble metal salt aqueous solution while maintaining the pH of the aqueous solution at around 4 to 9.

In this case, the metal salt forms an aluminum salt. In this case, Al and P ₃ O ₁₀ minutes charged respectively in the range of Al / 3P = 1.5 to 3.8 are almost entirely precipitated as an aluminum salt. It is considered possible to obtain an aluminum salt of tripolyphosphoric acid having an Al / 3P ratio that is substantially equal to the Al / 3P ratio of the raw material usage ratio. The aluminum salt of tripolyphosphoric acid thus obtained is an amorphous white powder that is substantially insoluble in water and has a specific surface area of 3
0 to 90 m ² / g, several nm from electron micrograph
It is confirmed that the particles are formed of the fine particles. The pH of the water slurry of the above substances is almost neutral (pH =
5.0 to 6.0), which is exhibited by crystalline aluminum tripolyphosphate obtained by the firing method (pH = 2.3).
It does not show such properties as a solid acid.

Since the composition of the present invention does not have active hydrogen which layered phosphates such as aluminum tripolyphosphate have, it has excellent storage stability of the paint even when compounded in a water-based paint, and has anticorrosive performance. Is excellent.

It is known that each of the layered phosphates has an active hydrogen atom, reacts with various basic substances, and intercalates guest molecules between layers.

In general, water-based paints use ammonia or amines to maintain a weakly basic pH in order to stabilize the resin.

Therefore, when these layered phosphates having active hydrogen are used as a rust preventive pigment in a water-based paint, they react with ammonia or amines or are taken in between the layers, which hinders the stabilization of the water-based resin. However, it causes poor storage stability of the paint.

In that respect, the rust preventive pigment composition according to the present invention is
Since it does not have such active hydrogen, it does not take in ammonia, amine, etc., and does not impair the stability of the paint even when used as an anticorrosion pigment in a water-based paint.

The rust preventive pigment composition of the present invention may further contain zinc oxide or an oxide or hydroxide of an alkaline earth metal for the purpose of further improving its rust preventive property. No special zinc oxide is required, and zinc oxide generally used for industry may be used. As the alkaline earth metal oxide or hydroxide, for example, magnesium oxide, magnesium hydroxide, magnesium carbonate, calcium oxide, calcium hydroxide, calcium carbonate or the like may be used, but especially magnesium oxide or water. Calcium oxide is preferred.

The proportion of the rust preventive pigment composition to be used in combination with the oxide or hydroxide of zinc oxide or alkaline earth metal is 10/1 to 1/10 by weight, particularly 10/1.
-10/10 is preferable. If the proportion of the rust-preventive pigment composition of the present invention is less than the above range, there is no combined effect, and conversely if the proportion is large, the dissolved metal ions of zinc and alkaline earth metals increase, so storage stability in water-based paints increases. Be hindered. The mixing method for the combined use may be either dry mixing or wet mixing. Alternatively,
Before being dispersed in the paint resin, they may be separately added to the paint resin so that they are mixed in the resin. However, when it is used for an aqueous coating composition, which tends to have a problem of storage stability, it is preferable to carry out wet mixing in advance before dispersing it in a coating resin.

The above-mentioned wet mixing may be carried out batchwise or continuously, and the order of addition of the components in the mixing may be added first. The temperature at the time of mixing is suitably in the range of room temperature to 80 ° C., and the time is usually preferably 30 minutes to 3 hours. After the mixing is completed, the slurry is filtered and dried, and the obtained dried product is pulverized to obtain the target product.

The wet mixing can be carried out subsequently after filtering the precipitate of the metal salt of tripolyphosphate and before drying. That is, the water-containing filter cake may be dispersed again in the aqueous solution, zinc oxide or an oxide of an alkaline earth metal may be added, and mixed under the above conditions.

The rust-preventive pigment composition of the present invention can have excellent storage stability, especially when used in water-based paints. However, when it comes to paints, water-soluble resins, dispersion resins,
Not only water-based resins such as emulsion resins (including emulsion resins for cationic electrodeposition coatings and emulsion resins for anion electrodeposition coatings) but also resins for coatings can be used without particular limitation. . For example, boil oil, oil varnish, phenolic resin,
Amino resin, epoxy resin, urethane resin, vinyl resin, acrylic resin, fluorine resin, silicone resin, polyester resin and other synthetic resins for paints, chlorinated rubber, rubber derivatives such as cyclized rubber, and other fibrin derivatives Or in combination.

[0029]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those examples. In the following, the number of parts indicating the amount and% indicating the concentration are based on the weight.

Example 1. (Molar ratio Al / 3P = 1.
7) 12 parts of sodium tripolyphosphate is added to 1000 g of water.
5 g was added and stirred to be completely dissolved to prepare a sodium tripolyphosphate aqueous solution. To this aqueous solution, polyaluminum chloride solution (PAC: 10.5% in terms of Al ₂ O ₃ )
276 g was added, hydrochloric acid was added until the pH reached 4, and the mixture was stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, and then the dehydrated cake was washed with water 10
00 g was added, the temperature was raised to 60 ° C., and the mixture was stirred for 1 hour. After stirring, the slurry solution is dehydrated, filtered, and washed at 90 ° C for 3 hours.
After drying for 6 hours, it was pulverized to obtain a rust preventive pigment composition.

Example 2. (Molar ratio Al / 3P = 2.
7) 12 parts of sodium tripolyphosphate is added to 1000 g of water.
5 g was added and stirred to be completely dissolved to prepare a sodium tripolyphosphate aqueous solution. To this aqueous solution, polyaluminum chloride solution (PAC: 10.5% in terms of Al ₂ O ₃ )
496 g was added and the mixture was stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, and then the dehydrated cake was charged with 1000 g of water again, heated to 60 ° C., and stirred for 1 hour. The slurry solution after stirring was dehydrated, filtered, dried at 90 ° C. for 36 hours, and then pulverized to obtain an antirust pigment composition.

Example 3. (Molar ratio Al / 3P = 2.7
ZnO mixture) 12 g of sodium tripolyphosphate for 1000 g of water
5 g was added and stirred to be completely dissolved to prepare a sodium tripolyphosphate aqueous solution. To this aqueous solution, polyaluminum chloride solution (PAC: 10.5% in terms of Al ₂ O ₃ )
496 g was added and the mixture was stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, and then 2000 g of water was added to the dehydrated cake again, the temperature was raised to 60 ° C., 50 g of zinc oxide was added, and wet mixing was performed for 1 hour. After the mixing treatment, the slurry solution is dehydrated and filtered,
After drying for 36 hours, it was pulverized to obtain a rust preventive pigment composition.

Example 4. (Molar ratio Zn / 3P = 2.
5) 50 g of sodium tripolyphosphate to 500 g of water
The mixture was charged and stirred, and completely dissolved to prepare an aqueous sodium tripolyphosphate solution. Further, 46 g of zinc chloride (ZnCl ₂ ) was added to 200 g of water, stirred and completely dissolved to prepare a zinc chloride aqueous solution. A zinc chloride aqueous solution was added to the sodium tripolyphosphate aqueous solution and stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, then added again to 500 g of water, heated to 60 ° C., and stirred for 1 hour. The slurry solution after stirring was dehydrated, filtered, dried at 90 ° C. for 36 hours, and then pulverized to obtain an antirust pigment composition.

Example 5. (Molar ratio Fe / 3P = 2.
5) 50 g of sodium tripolyphosphate to 700 g of water
The mixture was charged and stirred, and completely dissolved to prepare an aqueous sodium tripolyphosphate solution. Further, 90 g of ferric sulfate (FeSO ₄ .7H ₂ O) was added to 200 g of water, stirred and completely dissolved to prepare an iron sulfate aqueous solution. An aqueous solution of iron sulfate was added to the aqueous solution of sodium tripolyphosphate and stirred for 30 minutes to form a precipitate. The precipitate formed was dehydrated and filtered, then added again to 1000 g of water and stirred for 1 hour. After stirring, the slurry solution is dehydrated, filtered, and heated to 90 ° C.
After drying for 36 hours, it was pulverized to obtain a rust preventive pigment composition.

Example 6. (Molar ratio Ca / 3P = 2.
5) 50 g of sodium tripolyphosphate to 500 g of water
The mixture was charged and stirred, and completely dissolved to prepare an aqueous sodium tripolyphosphate solution. Further, 50 g of calcium chloride (CaCl ₂ .2H ₂ O) was added to 200 g of water, stirred and completely dissolved to prepare calcium chloride. An aqueous solution of calcium chloride was added to the aqueous solution of sodium tripolyphosphate and stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, then added again to 500 g of water, heated to 60 ° C., and stirred for 1 hour. The slurry solution after stirring was dehydrated, filtered, dried at 90 ° C. for 36 hours, and then pulverized to obtain an antirust pigment composition.

Example 7. (Molar ratio Mg / 3P = 2.
5) 50 g of sodium tripolyphosphate to 500 g of water
The mixture was charged and stirred, and completely dissolved to prepare an aqueous sodium tripolyphosphate solution. Further, 69 g of magnesium chloride (MgCl ₂ .6H ₂ O) was added to 200 g of water and stirred to completely dissolve it to prepare a magnesium chloride aqueous solution. An aqueous solution of magnesium chloride was added to the aqueous solution of sodium tripolyphosphate and stirred for 30 minutes to form a precipitate. The formed precipitate was dehydrated and filtered, and then water was added again.
The mixture was added to 0 g, heated to 60 ° C., and stirred for 1 hour. After stirring, the slurry solution is dehydrated, filtered, and washed at 90 ° C.
After drying for 6 hours, it was pulverized to obtain a rust preventive pigment composition.

Comparative Example 1. Blank (talc)

Comparative Example 2. K-100P manufactured by Teika (calcined aluminum tripolyphosphate)

Comparative Example 3. TAYCA K-105 (calcined aluminum tripolyphosphate / zinc treated product)

Comparative Example 4. Zinc phosphate

Table 1 shows the pH of the water slurries of Examples 1 to 7 and Comparative Examples 1 to 4.

The pH of the water slurry is JIS K5101.
The measurement was carried out according to the pigment test method of. That is, sample 5
g was added to 100 ml of water, boiled for 5 minutes, cooled to room temperature, and pH was measured.

[0043]

[Table 1]

Using the anticorrosive pigment compositions of Examples 1 to 7 and the pigment compositions of Comparative Examples 1 to 4, as test examples, normally dry emulsion resin-based paints were prepared, and after forming a coating film, A salt spray test was performed. In addition, a storage stability test of the paint was conducted separately.

Test Example An ordinary dry emulsion resin-based paint having the composition shown in Table 2 was prepared, and after forming a coating film, a salt spray test and a storage stability test were conducted.

1-1 Preparation of Paints 11 kinds of normally dry emulsion resin-based paints were prepared with the formulations shown in Table 2.

[0047]

[Table 2]

1-2 Coating and Coating Conditions Each of the 11 kinds of normally dry emulsion resin-based paints was coated on a plate to be coated under the following conditions and dried at room temperature to form a coating film. Coating: Bar coater coated plate: Degreasing mild steel plate JIS G 3141
(SPCC-SB) Japan Test Panel Industry Co., Ltd. film thickness: 38 to 42 μm Drying: room temperature, 7 days

1-3 Salt Spray Test A test plate prepared by forming a coating film on a plate to be coated as described above was placed in a salt spray tester whose internal temperature was kept at 35 ° C. and a 5% sodium chloride aqueous solution. 1 kg / c
The coating film was sprayed at m ² for 10 days, and the generation of rust on the test plate and the swelling of the coating film were observed.

1-4 Results of Salt Spray Test The results of the salt spray test are shown in Table 3 for each type of rust preventive pigment. The rust preventive effect is evaluated by the rust preventive effect on the test plate and the swelling preventive effect on the coating film.
It is as follows. The evaluation criteria for the effect of preventing rust is based on ASTM D610-68 (1970),
The evaluation criteria for the blistering prevention effect are ASTM D714-5.
9 (1965). As is clear from the following evaluation criteria, the higher the evaluation value is, the better the effect of preventing rust and the effect of preventing swelling are.

Evaluation criteria for rust prevention effect 5: Rust generation area less than 0.1% 4: Rust generation area 0.1% to less than 1% 3: Rust generation area 1% or more and less than 10% 2: Rust generation area 10% to less than 33% 1: Rust generation area 33% or more Evaluation criteria for blistering prevention effect 5: 8F or more 4: 8M, 6F, 4F 3: 8MD, 6M 2: 8D, 6MD, 4M, 2F 1: 6D, 4MD or more, 2M or more

[0052]

[Table 3]

1-5 Storage Stability Test of Paints Paints containing various anticorrosive pigments were prepared with the above-mentioned composition . This paint was left in a thermostatic chamber at 40 ° C., and the viscosity of each paint was measured every week for one month with a B-type viscometer.

1-6 Results of Storage Stability Test of Paints The results of the above storage stability test are shown in Table 4 for each type of rust preventive pigment. As an evaluation, it is preferable that the viscosity change with time is small, and if the viscosity change is extremely large, the coating may gel and cannot be used. The unit of the numbers in Table 4 is cps.

[0055]

[Table 4]

As shown in Table 3, the rust preventive pigment compositions of Examples 1 to 7 were excellent in the rust preventive effect and the swell preventive effect. Moreover, as shown in Table 4, the rust preventive pigment compositions of Examples 1 to 7 showed little increase in viscosity upon storage and were excellent in storage stability in the water-based paint.

On the other hand, Comparative Example 1. The blank (in which the rust preventive pigment component was replaced with talc having no rust preventive effect) and the zinc phosphate of Comparative Example 4 had good storage stability, but had a low rust preventive effect. The solid acidic aluminum tripolyphosphate obtained by the firing method of Comparative Example 2 has poor storage stability and rust resistance, and the composition treated with zinc oxide containing the solid acidic aluminum tripolyphosphate obtained by the firing method of Comparative Example 3 as a main component. The product had an excellent rust preventive effect, but the storage stability of the paint was poor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Ogami             Osaka Prefecture Osaka City Taisho-ku Funamachi 1-3-47             Inside the Teika Co., Ltd. F term (reference) 4J037 AA08 AA14 AA25 CA05 CA09                       CA11 CA12 CA18 CA21 EE28                       EE43 FF24                 4J038 BA201 CA001 CA041 CD091                       CE001 CF001 CG001 DA151                       DB001 DD001 DG001 DL001                       HA146 HA156 HA266 HA426                       KA06 KA08 KA18 MA08 NA03                       NA26 NA27 PB14 PC02                 4K062 AA01 BA08 BA09 BA11 BA20                       BC04 BC11 CA04 FA12 GA08

Claims (7)

[Claims] 1. A rust preventive pigment composition comprising a poorly water-soluble reaction product of sodium tripolyphosphate and a water-soluble polyvalent metal salt in an aqueous solution. 2. The rust preventive pigment composition according to claim 1, wherein the metal species of the water-soluble polyvalent metal salt is selected from alkaline earth metals, aluminum, zinc, cerium or iron. 3. The molar ratio M / P3 of the polyvalent metal M of the poorly water-soluble reaction product to the tripolyphosphate P3 is 0.5 to.
The rust preventive pigment composition according to claim 1 or 2, which is 10. 4. A method for producing a rust preventive pigment composition, which comprises reacting sodium tripolyphosphate with a water-soluble polyvalent metal salt in an aqueous solution, and filtering the resulting precipitate, washing, drying and pulverizing. 5. The method according to claim 4, wherein the metal species of the water-soluble polyvalent metal salt is selected from alkaline earth metals, aluminum, zinc, cerium, or iron. 6. The method according to claim 4, wherein the reaction molar ratio of the water-soluble polyvalent metal salt to sodium tripolyphosphate is 0.5 to 10. 7. A water-based anticorrosive paint obtained by dispersing the anticorrosive pigment composition according to claim 1 in a vehicle for water-based paint.