Long-acting electrophoretic paint anti-corrosion pigment and preparation method thereof

Abstract

The invention discloses a long-acting electrophoretic paint anti-corrosion pigment and a preparation method thereof, and belongs to the technical field of anti-corrosion pigments. The preparation method comprises the following steps: respectively preparing slurry from 10-30 parts of phytic acid phosphomolybdic acid double salt, 60-80 parts of mica or silica powder and 10-20 parts of bismuth hydroxide, sequentially mixing the slurry, and adding a silane coupling agent for surface treatment; and washing the product with deionized water after filter pressing, and then drying to obtain the long-acting electrophoretic paint anti-corrosion pigment. A coated object and a coated object product prepared from all the raw materials of the anti-corrosion pigment are environment-friendly and non-toxic, do not contain toxic heavy metal components such as lead, chromium, cadmium, tin, arsenic, mercury and the like and non-soluble conductive ions, and do not cause harm to human health and the environment when being produced and used.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion pigments, in particular to a long-lasting electrophoretic paint anti-corrosion pigment and a preparation method thereof. Background Art

[0002] Electrophoretic coating is the earliest developed water-based coating. Its characteristics are high coating rate, economic safety, low pollution, and full automation. Electrophoretic coating has long been widely used in the production lines of automobile factories around the world.

[0003] The anti-corrosion pigments used in electrophoretic coatings are designed to form a protective film on the surfaces of steel and light alloys through electrophoretic coating, preventing corrosion. The key requirements for electrophoretic coatings include preventing corrosion of steel and light alloys, ensuring that the metal ions in the anti-corrosion pigments are not easily dissolved in the aqueous composition and precipitated during the coating process to prevent viscosity increase and gelation, thereby maintaining the throwing power and coating appearance quality. Furthermore, the interaction of dissolved metal ions with the anions in the aqueous composition can reduce throwing power and produce defects such as orange peel. Therefore, both excellent anti-corrosion performance and minimal soluble conductive ions are required. Therefore, special attention must be paid to the selection and application conditions of anti-corrosion pigments to ensure the quality and effectiveness of electrophoretic coatings. To avoid this, measures must be taken to ensure the stability of the anti-corrosion pigments in the electrophoretic coating. Currently, the commonly used anti-corrosion pigments in electrophoretic coatings include basic lead silicate chromate, strontium chromate, barium chromate, zinc phosphate, and aluminum phosphate. Among these anti-corrosion pigments, those containing heavy metals such as chromium, lead, tin, and cadmium have excellent anti-corrosion properties, good stability, and excellent overall performance, and have always been the first choice for electrophoretic coatings. However, due to their toxicity, which poses a threat to human safety and the environment, their use has gradually been banned. Other non-toxic anti-corrosion pigments have unsatisfactory anti-corrosion properties and are difficult to completely replace toxic anti-corrosion pigments in high-corrosion protection applications. Foreign companies such as Kansai in Japan and PPG in the United States have developed alternative products that do not contain heavy metals such as chromium and lead. Their anti-corrosion properties are as good as those of pigments containing heavy metals, but they are more expensive, sometimes very high, and difficult to purchase.

[0004] Therefore, providing a cheap, environmentally friendly, long-lasting anti-corrosion pigment for electrophoretic coatings is a problem that those skilled in the art continue to solve. Summary of the Invention

[0005] In view of this, the present invention provides a long-lasting electrophoretic paint anti-corrosion pigment and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A long-lasting electrophoretic paint anti-corrosion pigment, comprising the following raw materials in parts by weight:

[0008] Phytic acid / phosphomolybdic acid double salt 10-30 parts, mica or silica powder 60-80 parts, bismuth hydroxide 10-20 parts.

[0009] Furthermore, the phytate in the phytic acid / phosphomolybdic acid double salt is any one of zinc phytate, aluminum phytate, iron phytate, manganese phytate, titanium phytate, nickel phytate, barium phytate and dilute thorium phytate;

[0010] The phosphomolybdate is any one of zinc phosphomolybdate, aluminum phosphomolybdate, iron phosphomolybdate, manganese phosphomolybdate, titanium phosphomolybdate, barium phosphomolybdate, and dilute thorium phosphomolybdate.

[0011] Furthermore, the ratio of phytate to phosphomolybdate in the phytic acid / phosphomolybdic acid double salt is 1:10-12.

[0012] Preferably, in the present invention, the preparation method of phytic acid / phosphomolybdic acid double salt is to mix phytic acid and phosphomolybdic acid in a mass ratio of 1:10 to 12, and then add the corresponding metal salt to react;

[0013] The metal salts are metal salts corresponding to zinc, aluminum, iron, manganese, titanium, barium and dilute thorium that can react with phytic acid and phosphomolybdic acid.

[0014] In the technical solution of the present invention, the effect of different metal salts on product performance is essentially negligible. Furthermore, during the research process, it was found that preparing phytate and phosphomolybdic acid separately and then mixing them did not produce a product with good corrosion resistance. However, a long-lasting electrophoretic paint anti-corrosion pigment prepared by first mixing phytic acid and phosphomolybdic acid and then adding the metal salt to the reaction had a much better corrosion resistance.

[0015] The present invention also provides a method for preparing the above-mentioned long-lasting electrophoretic paint anti-corrosion pigment, comprising the following steps:

[0016] (1) Weigh each raw material according to the above parts by weight;

[0017] (2) preparing slurries of phytic acid / molybdophosphate double salt, mica or silica powder, and bismuth hydroxide;

[0018] (3) adding the bismuth hydroxide slurry to the mica or silica powder slurry and stirring uniformly to obtain a first mixed slurry;

[0019] (4) adding the phytic acid / phosphomolybdic acid double salt slurry to the first mixed slurry, stirring again to uniformity, and then adding a silane coupling agent for surface treatment;

[0020] (5) After filtration, the product is washed with deionized water and then dried to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0021] Furthermore, in step (2), the particle size of the phytic acid / phosphomolybdic acid double salt is less than 1 micron, the particle size of the mica or silica powder is less than 5 microns, and the particle size of the bismuth hydroxide is less than 1 micron.

[0022] Furthermore, in step (2), the particle size of the phytic acid\phosphomolybdic acid double salt slurry is less than 1 micron, the particle size of the mica or silica powder slurry is less than 5 microns, and the particle size of the bismuth hydroxide slurry is less than 1 micron.

[0023] Furthermore, the amount of the silane coupling agent in step (4) is 2-3% of the total mass of phytic acid / molybdophosphate complex salt, mica or silicon powder and bismuth hydroxide.

[0024] Furthermore, the silane coupling agent is KH550 type silane coupling agent.

[0025] Furthermore, in step (5), the product is washed with deionized water until there is no conductive ion in the product.

[0026] The beneficial effects of the present invention are that the coated materials and coated products made from all raw materials of the anti-corrosion pigment of the present invention are environmentally friendly and non-toxic, do not contain toxic heavy metal components such as lead, chromium, cadmium, tin, arsenic, mercury, and no soluble conductive ions, and will not cause harm to human health and the environment during the production and use of the long-lasting electrophoretic anti-corrosion pigment of the present invention.

[0027] The long-lasting electrophoretic anti-corrosion pigment of the present invention is now used to make electrophoretic paint with domestic and foreign electrophoretic anti-corrosion pigments, and the electrophoretic workpiece is subjected to anti-corrosion performance testing and cost-effectiveness test as follows: Note: In order to facilitate the test of corrosion resistance, the thickness of the electrophoretic paint film of the test workpiece is not electrophoresed according to the standard thickness of the electrophoretic paint film.

[0028]

[0029] DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] Weigh 70 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10), 880 g of mica, and 50 g of bismuth hydroxide, prepare the phytic acid / phosphomolybdic acid double salt into a slurry of less than 1 micron, prepare the mica into a slurry of less than 5 microns, and prepare the bismuth hydroxide into a slurry of less than 1 micron. Add the bismuth hydroxide slurry to the mica slurry under rapid stirring, and then add 3% of a silane coupling agent to the mica slurry to which the phytic acid / phosphomolybdic acid salt slurry is added under rapid stirring for surface treatment, followed by filter pressing, washing with deionized water, and drying to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0033] Example 2

[0034] Weigh 100 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10), 870 g of mica, and 30 g of bismuth hydroxide, prepare the phytic acid / phosphomolybdic acid double salt into a slurry less than 1 micron, prepare the mica into a slurry less than 5 microns, and prepare the bismuth hydroxide into a slurry less than 1 micron. Add the bismuth hydroxide slurry to the mica slurry under rapid stirring, and then add 2% of a silane coupling agent to the mica slurry to which the phytic acid / phosphomolybdic acid salt slurry is added under rapid stirring for surface treatment, followed by filter pressing, washing with deionized water, and drying to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0035] Example 3

[0036] Weigh 150 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10), 830 g of mica, and 20 g of bismuth hydroxide, respectively, and make the phytic acid / phosphomolybdic acid double salt into a slurry of less than 1 micron, the mica into a slurry of less than 5 microns, and the bismuth hydroxide into a slurry of less than 1 micron. The bismuth hydroxide slurry is added to the mica slurry under rapid stirring, and then the mica slurry to which the phytic acid / phosphomolybdic acid salt slurry is added is added with 2% silane coupling agent under rapid stirring for surface treatment, followed by filter pressing, washing with deionized water, and drying to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0037] Example 4

[0038] Weigh 200 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10), 760 g of mica, and 40 g of bismuth hydroxide, respectively, and make the phytic acid / phosphomolybdic acid double salt into a slurry of less than 1 micron, the mica into a slurry of less than 5 microns, and the bismuth hydroxide into a slurry of less than 1 micron. The bismuth hydroxide slurry is added to the mica slurry under rapid stirring, and then the mica slurry to which the phytic acid / phosphomolybdic acid salt slurry is added is added with 3% of a silane coupling agent under rapid stirring for surface treatment, followed by filter pressing, washing with deionized water, and drying to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0039] Example 5

[0040] Weigh 150 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10), 820 g of silicon powder, and 30 g of bismuth hydroxide. Prepare the phytic acid / phosphomolybdic acid double salt into a slurry of less than 1 micron, the silicon powder into a slurry of less than 5 microns, and the bismuth hydroxide into a slurry of less than 1 micron, respectively. Add the bismuth hydroxide slurry to the silicon powder slurry under rapid stirring, and then add 2% of a silane coupling agent to the silicon powder slurry to which the phytic acid / phosphomolybdic acid salt slurry is added under rapid stirring for surface treatment. The mixture is then filtered, washed with deionized water, and dried to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0041] Example 6

[0042] Weigh 210 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10) and 790 g of silicon powder, respectively, prepare the phytic acid / phosphomolybdic acid double salt into a slurry of less than 1 micron, the silicon powder into a slurry of less than 5 microns, and the bismuth hydroxide into a slurry of less than 1 micron, and add the bismuth hydroxide slurry to the silicon powder slurry under rapid stirring. Then, add 2% of a silane coupling agent to the silicon powder slurry to which the phytic acid / phosphomolybdic acid salt slurry is added under rapid stirring for surface treatment, and then filter press, wash with deionized water, and dry to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0043] Example 7

[0044] Weigh 260 g of phytic acid / phosphomolybdic acid double salt (phytic acid: phosphomolybdic acid = 1:10) and 740 g of silicon powder, respectively prepare the phytic acid / phosphomolybdic acid double salt into a slurry of less than 0.1 micron and the silicon powder into a slurry of less than 5 micron, add the phytic acid / phosphomolybdic acid salt slurry to the silicon powder slurry, add 3% silane coupling agent under rapid stirring for surface treatment, then filter press, wash with deionized water, and dry to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

[0045] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A long-lasting electrophoretic paint anti-corrosion pigment, characterized in that: It includes the following raw materials in parts by weight: Phytic acid / phosphomolybdic acid double salt 10-30 parts, mica or silica powder 60-80 parts, bismuth hydroxide 10-20 parts.

2. The long-lasting electrophoretic paint anti-corrosion pigment according to claim 1, characterized in that: The phytate in the phytic acid / phosphomolybdic acid double salt is any one of zinc phytate, aluminum phytate, iron phytate, manganese phytate, titanium phytate, nickel phytate, barium phytate and dilute thorium phytate; The phosphomolybdate is any one of zinc phosphomolybdate, aluminum phosphomolybdate, iron phosphomolybdate, manganese phosphomolybdate, titanium phosphomolybdate, barium phosphomolybdate, and dilute thorium phosphomolybdate.

3. The long-lasting electrophoretic paint anti-corrosion pigment according to claim 2, characterized in that: The ratio of phytate to phosphomolybdate in the phytic acid / phosphomolybdic acid double salt is 1:10-12.

4. A method for preparing a long-lasting anti-corrosion pigment for electrophoretic paint, characterized in that: The following steps are involved: (1) Weighing each raw material according to the weight parts described in any one of claims 1 to 3; (2) preparing slurries of phytic acid / molybdophosphate double salt, mica or silica powder, and bismuth hydroxide; (3) adding the bismuth hydroxide slurry to the mica or silica powder slurry and stirring uniformly to obtain a first mixed slurry; (4) adding the phytic acid / phosphomolybdic acid double salt slurry to the first mixed slurry, stirring again to uniformity, and then adding a silane coupling agent for surface treatment; (5) After filtration, the product is washed with deionized water and then dried to obtain a long-lasting electrophoretic paint anti-corrosion pigment.

5. The method for preparing a long-lasting electrophoretic paint anti-corrosion pigment according to claim 4, characterized in that: In step (2), the particle size of the phytic acid / phosphomolybdic acid double salt slurry is less than 1 micron, the particle size of the mica or silicon micropowder slurry is less than 5 microns, and the particle size of the bismuth hydroxide slurry is less than 1 micron.

6. The method for preparing a long-lasting anti-corrosion pigment for electrophoretic paint according to claim 4, characterized in that: The amount of the silane coupling agent used in step (4) is 2-3% of the total mass of phytic acid / molybdophosphate salt, mica or silicon powder and bismuth hydroxide.

7. The method for preparing a long-lasting anti-corrosion pigment for electrophoretic paint according to claim 6, characterized in that: The silane coupling agent in step (4) is KH550 type silane coupling agent.

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