CN102775833A - Nanometer oxide coated phosphate rust resisting pigment and preparation method thereof - Google Patents

Abstract

The invention discloses a nano-scale oxide-coated phosphate anti-rust pigment, which is a composite anti-rust pigment formed by coating nano-scale oxide on micro-scale phosphate; nano-scale oxide and micro-scale phosphate The weight ratio is (1-10):100. The preparation steps include: A. Calcium-containing compound and phosphoric acid react in liquid phase to prepare calcium phosphate; B. Add titanyl sulfate or zinc sulfate solution into the calcium phosphate solution and stir evenly, and then mix calcium hydroxide emulsion Slowly drop it into it, and the generated nano-titanium dioxide or nano-zinc oxide is coated on the surface of calcium phosphate; C. Filter the reaction solution, and the filter cake is dried and roasted to obtain the product. The antirust pigment of the invention not only has excellent metal antirust performance, but also has very low price.

Description

Nano-oxide-coated phosphate antirust pigment and preparation method thereof

technical field

The invention relates to the technical field of metal antirust, in particular to an antirust pigment.

Background technique

The annual economic loss caused by metal corrosion in the world is as high as 700 billion U.S. dollars, which is higher than the sum of natural disaster losses such as earthquakes, fires, and typhoons. In our country, the loss caused by metal corrosion is also huge, accounting for about 4% of the gross national product. In order to prevent corrosion of metals, a variety of protective measures such as biological measures, metallurgy, electrochemical measures and paint protection measures can be used. Among them, coating the metal surface with an anti-corrosion coating is one of the most effective and commonly used methods to prevent metal corrosion. This is because the use of coating protection has strong applicability and is relatively economical. In addition, it can combine protection with decoration and other effects. stand up.

The protection of metal corrosion by coatings not only depends on the selected resin system, but also depends to a large extent on the selected anti-rust pigments. Therefore, the anti-corrosion performance of coatings is the result of the interaction between the resin system and anti-rust pigments. At present, there are many kinds of antirust pigments on the market, which can be basically divided into three categories: inert antirust pigments (shielding pigments), sacrificial pigments, and active antirust pigments:

1. Inert pigments play a physical role, which can enhance the shielding effect of the coating film. Generally speaking, they are chemically inert;

2. Sacrificial pigments are metal pigments, which belong to a special category of active pigments. They are sprayed on iron substrates and exert antirust performance through cathodic protection;

3. Active pigments prevent metal corrosion through chemical and (or) electrochemical actions, and are the mainstream of antirust pigments, and the present invention belongs to this category.

Reactive pigments interact directly or through intermediates with the metal substrate to slow down corrosion, they have the role of maintaining the pH value of the coating, saponification reaction and passivation of the metal. There are many types of active antirust pigments, mainly including: lead pigments (such as red lead), chromium pigments (such as zinc chrome yellow, lead chrome yellow, etc.), phosphate, molybdate, metaborate, etc.

For a long time, although the antirust pigments containing lead and chromium (VI) and other toxic heavy metals used in the paint industry have excellent antirust performance, they are highly toxic and dark in color, and the antirust primer configured requires a surface with high hiding power. The matching of paint has brought great difficulties to the deep processing of the paint industry. In addition, the three wastes produced in the production process of lead and chromium (Ⅵ) pigments, the dust produced in the paint making process, the gas emitted during welding and cutting after metal painting, and the toxic paint film after the coating is damaged, etc. will all be harmful to the human body. and the environment cause serious harm and pollution, therefore, the production and use of such pigments are gradually restricted. With the increasingly stringent and perfect environmental legislation, labor protection regulations and industrial hygiene standards in various countries around the world, it has become a consensus to seek non-toxic or low-toxic ecological anti-rust pigments and gradually replace traditional toxic anti-rust pigments.

In 1906, British scholar Coslett T W. invented the treatment method of using phosphate as an antirust agent for the purpose of preventing steel from rusting. In 1959, Harrison J B. in the United Kingdom conducted an industrial application test on zinc phosphate antirust pigments for the first time. In 1972, Japan took the public nuisance problem as an opportunity to start using aluminum polyphosphate series non-toxic anti-rust pigments to replace toxic pigments such as chromate and lead red containing chromium and lead, and then gradually popularized them in my country, Western Europe, the United States and other countries. So far, a variety of pigments such as phosphate series, molybdate series and borate series have been developed and developed, among which phosphate series pigments have greater advantages in terms of their varieties, performance and application range. Thus making it the largest amount of non-toxic anti-rust pigments.

For example, pigment companies in Germany, the United States, Japan, and several related companies led by Hebei University in China have successively launched a series of new antirust pigments such as zinc phosphate, modified zinc phosphate, and polyaluminum phosphate since the late 1980s. The anti-rust performance is equivalent to or better than the traditional lead-based and chrome-based toxic anti-rust pigments. But the main problem at present is that the cost of these phosphate antirust pigments is quite high (for example, the current market price of zinc phosphate is 15,000 yuan/ton, and the price of polyaluminum phosphate is 13,000 yuan/ton), making these non-toxic antirust pigments Widespread use and promotion are limited.

Contents of the invention

The technical problem to be solved by the present invention is to provide a nano-oxide-coated phosphate antirust pigment, which not only has excellent metal antirust performance, but also has a very low price; for this reason, the present invention also provides the preparation of the antirust pigment method.

In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

Nano oxide coated phosphate antirust pigment, the antirust pigment is a composite antirust pigment formed by coating nanoscale oxide on micron phosphate; the weight ratio of nanoscale oxide to micron phosphate is (1 -10): 100.

As a preferred technical solution of the present invention, the oxide is titanium dioxide or zinc oxide with a particle size of 2-30 nm; the phosphate is calcium phosphate with a particle size of 0.3-5 μm.

The preparation method of above-mentioned nano-oxide coating phosphate antirust pigment, its step comprises:

A, calcium-containing compound and phosphoric acid prepare calcium phosphate by liquid phase reaction;

B. Add titanium oxysulfate or zinc sulfate solution into the calcium phosphate emulsion and stir evenly, then slowly drop the calcium hydroxide emulsion into it while stirring, and the generated nano-titanium dioxide or nano-zinc oxide is coated on calcium phosphate surface;

C. Filter the reaction solution, and dry and roast the filter cake to obtain the product.

As a preferred technical scheme of the above-mentioned preparation method, the specific operation method of step A is:

A-1. Weigh calcium carbonate, calcium hydroxide or calcium oxide, add water and stir to form a uniform emulsion;

A-2. Measure 85% concentrated phosphoric acid according to the molar ratio P:Ca=2:3, add double water to dilute, and stir evenly;

A-3. Slowly drop the phosphoric acid solution in step A-2 into the calcium-containing compound emulsion in step A-1, and stir for 1-3 hours to obtain a calcium phosphate emulsion.

As a preferred technical scheme of the above-mentioned preparation method, the specific operation method of step B is:

B-1. Weigh titanyl sulfate or zinc sulfate, add water to dissolve for subsequent use; wherein, the weight ratio of titanyl sulfate or zinc sulfate to calcium phosphate obtained in step A is (2-20):100;

B-2, take calcium hydroxide, add water and be mixed with emulsion for subsequent use; Wherein, the weight ratio of calcium hydroxide and step A gained calcium phosphate is (0.1-0.9):1;

B-3. Add the titanyl sulfate or zinc sulfate solution in step B-1 into the calcium phosphate emulsion in step A and stir evenly, then slowly drop the calcium hydroxide emulsion in step B-2 into it while stirring , the generated nano-titanium dioxide or nano-zinc oxide is coated on the surface of calcium phosphate.

As a preferred technical solution of the above preparation method, in step C, the drying temperature is 100°C, the calcination temperature is 300°C, and the calcination time is 0.5-2h.

The beneficial effects produced by adopting the above-mentioned technical scheme are:

①Analysis and summary of the beneficial effects of the present invention: From theoretical analysis and in the process of preparing antirust coatings, it is found that the "composite" of antirust pigments and the "matching" of pigment particle sizes are very important to the influence of coating film performance. If two or more materials are selected, one of them can use a pigment with a larger particle size and a lower price as the main material, and the other or several can use a material with a relatively small particle size as a dispersed phase auxiliary material, so that It can not only achieve the "composite" of materials, but also achieve the purpose of "matching" particle size. In the metal antirust system, coatings are mainly used to prevent the oxidation and corrosion of metals by oxygen, water and chloride ions, and to block the electrochemical corrosion of metals by current flow. If nanomaterials are used as the dispersed phase and dispersed into the coating with a reasonable ratio, the performance of this coating will definitely exceed that of conventional coatings. Obviously, it is feasible to use nanotechnology to develop non-toxic, cost-effective anti-rust pigments through composite modification. Due to the unique properties of nanomaterials, the use of nanomaterials in coatings can obtain a variety of special properties, such as improving the aging resistance, corrosion resistance, and radiation resistance of coatings, and can further improve the adhesion of coatings. , strength, hardness, wear resistance, etc., thus greatly improving the performance of traditional coatings. The invention firstly prepares cheap calcium phosphate non-toxic anti-rust pigment intermediate by chemical precipitation method, and then uses co-precipitation technology to coat nano- _TiO2 or nano-ZnO coating on the surface of the pigment to make composite anti-rust pigment.

2. Verification of the beneficial effects of the present invention: the paint-making experiment proves that the nanocomposite phosphate series antirust pigments prepared by the present invention not only have low cost (about 3,000 yuan/ton), but also use it to prepare antirust coatings with all indicators reaching The national standard, especially salt spray resistance (the key indicator of anti-rust performance), is not only superior to the zinc phosphate pigments currently sold in the market, but also superior to the German ZPA anti-rust pigment; the specific test data is shown in the table below;

Table 1. The antirust performance test result of antirust pigment of the present invention

In addition, referring to accompanying drawing 1, it is the scanning electron microscope photo of the sample that is prepared for the embodiment of the present invention, can see from the photo, the particle diameter of main body calcium phosphate pigment is about 1-3 micron (nano-oxide coating is attached on the calcium phosphate ).

Description of drawings

Figure 1 is a scanning electron micrograph of the sample prepared in Example 1 of the present invention.

Detailed ways

The following examples illustrate the invention in detail. Various raw materials and various equipments used in the present invention are conventional commercially available products, and can be directly obtained through market purchase.

Example 1

The preparation method of antirust pigment of the present invention:

1: Weigh 22.3g of calcium hydroxide [Ca(OH) ₂ ], slowly add 200ml of water, stir well until the emulsification is uniform.

2: Measure 14ml of concentrated phosphoric acid with a concentration of 85%, slowly add 28ml of water, and stir evenly.

3: Slowly add the diluted phosphoric acid to the calcium hydroxide emulsion while stirring. After the dropwise addition, the stirring reaction was continued at normal temperature for 2 hours to stop, and the calcium phosphate intermediate emulsion was obtained.

4: Add 3.2g of titanium oxysulfate (TiOSO ₄ ) into 100ml of water, dissolve and set aside.

5: Weigh 2.86g of calcium hydroxide, add 50ml of water and stir to form an emulsion for later use.

6: Add the titanyl sulfate solution prepared in step 4 to the calcium phosphate intermediate emulsion prepared in step 3, mix evenly and drop into the calcium hydroxide emulsion prepared in step 5 while stirring, so that the generated titanium dioxide is coated on the calcium phosphate surface.

7: Filtration, drying the filter cake at 100°C. Then put it into a muffle furnace and bake at 300° C. for 1 hour to obtain nano-TiO ₂ coated calcium phosphate composite anti-rust pigment.

Example 2

The preparation method of antirust pigment of the present invention:

1: Weigh 30g of calcium carbonate [CaCO ₃ ], slowly add 200ml of water, stir well until the emulsification is uniform.

2: Measure 14ml of concentrated phosphoric acid with a concentration of 85%, slowly add 28ml of water, and stir evenly.

3: Slowly add the diluted phosphoric acid to the calcium hydroxide emulsion while stirring. After the dropwise addition, the stirring reaction was continued at normal temperature for 2 hours to stop, and the calcium phosphate intermediate emulsion was obtained.

4: Add 3.2g of titanium oxysulfate (TiOSO ₄ ) into 100ml of water, dissolve and set aside.

5: Weigh 2.86g of calcium hydroxide, add 50ml of water and stir to form an emulsion for later use.

6: Add the titanyl sulfate solution prepared in step 4 to the calcium phosphate intermediate emulsion prepared in step 3, mix evenly and drop into the calcium hydroxide emulsion prepared in step 5 while stirring, so that the generated titanium dioxide is coated on the calcium phosphate surface.

7: Filtration, drying the filter cake at 100°C. Then put it into a muffle furnace and bake at 300° C. for 1 hour to obtain nano-TiO ₂ coated calcium phosphate composite anti-rust pigment.

Example 3

The preparation method of antirust pigment of the present invention:

1: Weigh 16.8g of calcium oxide [CaO], slowly add 200ml of water, stir well until the emulsification is uniform.

2: Measure 14ml of concentrated phosphoric acid with a concentration of 85%, slowly add 28ml of water, and stir evenly.

3: Slowly add the diluted phosphoric acid to the calcium hydroxide emulsion while stirring. After the dropwise addition, the stirring reaction was continued at normal temperature for 2 hours to stop, and the calcium phosphate intermediate emulsion was obtained.

4: Add 3.2g of titanium oxysulfate (TiOSO ₄ ) into 100ml of water, dissolve and set aside.

5: Weigh 2.86g of calcium hydroxide, add 50ml of water and stir to form an emulsion for later use.

6: Add the titanyl sulfate solution prepared in step 4 to the calcium phosphate intermediate emulsion prepared in step 3, mix evenly and drop into the calcium hydroxide emulsion prepared in step 5 while stirring, so that the generated titanium dioxide is coated on the calcium phosphate surface.

7: Filtration, drying the filter cake at 100°C. Then put it into a muffle furnace and bake at 300° C. for 1 hour to obtain nano-TiO ₂ coated calcium phosphate composite anti-rust pigment.

Example 4

The preparation method of antirust pigment of the present invention:

1: Weigh 22.3g of calcium hydroxide [Ca(OH) ₂ ], slowly add 200ml of water, stir well until the emulsification is uniform.

2: Measure 14ml of concentrated phosphoric acid with a concentration of 85%, slowly add 28ml of water, and stir evenly.

3: Slowly add the diluted phosphoric acid to the calcium hydroxide emulsion while stirring. After the dropwise addition, the stirring reaction was continued at normal temperature for 2 hours to stop, and the calcium phosphate intermediate emulsion was obtained.

4: Add 3.2g of zinc sulfate (ZnSO ₄ ) into 100ml of water, dissolve and set aside.

5: Weigh 2.86g of calcium hydroxide, add 50ml of water and stir to form an emulsion for later use.

6: Add the titanyl sulfate solution prepared in step 4 to the calcium phosphate intermediate emulsion prepared in step 3, mix evenly and drop into the calcium hydroxide emulsion prepared in step 5 while stirring, so that the generated titanium dioxide is coated on the calcium phosphate surface.

7: Filtration, drying the filter cake at 100°C. Then put it into a muffle furnace and bake at 300° C. for 1 hour to obtain nano-TiO ₂ coated calcium phosphate composite anti-rust pigment.

The above description is only proposed as an implementable technical solution of the present invention, and not as a single restriction on the technical solution itself. In addition to coating nano-titanium dioxide and nano-zinc oxide, this technology can also be used to coat a series of nano-materials such as nano-iron oxide, nano-silicon oxide, and rare earth nano-oxides on the surface of phosphate pigments.

Claims (6)

1. Nano oxide coated phosphate antirust pigment, characterized in that: the antirust pigment is a composite antirust pigment formed by coating nanoscale oxide on micron phosphate; nanoscale oxide and micron phosphate The weight ratio is (1-10):100. 2. The nano oxide-coated phosphate antirust pigment according to claim 1, characterized in that: the oxide is titanium dioxide or zinc oxide, and its particle diameter is 2-30nm; the phosphate is calcium phosphate, Its particle size is 0.3-5 μm. 3. the preparation method of above-mentioned nano-oxide coating phosphate antirust pigment, its feature step comprises: A, calcium-containing compound and phosphoric acid prepare calcium phosphate by liquid phase reaction; B. Add titanium oxysulfate or zinc sulfate solution into the calcium phosphate emulsion and stir evenly, then slowly drop the calcium hydroxide emulsion into it while stirring, and the generated nano-titanium dioxide or nano-zinc oxide is coated on calcium phosphate surface; C. Filter the reaction solution, and dry and roast the filter cake to obtain the product. 4. the preparation method according to claim 3 is characterized in that: the specific operating method of step A is: A-1. Weigh calcium carbonate, calcium hydroxide or calcium oxide, add water and stir to form a uniform emulsion; A-2. Measure 85% concentrated phosphoric acid according to the molar ratio P:Ca=2:3, add double water to dilute, and stir evenly; A-3. Slowly drop the phosphoric acid solution in step A-2 into the calcium-containing compound emulsion in step A-1, and stir for 1-3 hours to obtain a calcium phosphate emulsion. 5. the preparation method according to claim 3 is characterized in that: the specific operating method of step B is: B-1. Weigh titanyl sulfate or zinc sulfate, add water to dissolve for subsequent use; wherein, the weight ratio of titanyl sulfate or zinc sulfate to calcium phosphate obtained in step A is (2-20):100; B-2, take calcium hydroxide, add water and be mixed with emulsion for subsequent use; Wherein, the weight ratio of calcium hydroxide and step A gained calcium phosphate is (0.1-0.9):1; B-3. Add the titanyl sulfate or zinc sulfate solution in step B-1 into the calcium phosphate emulsion in step A and stir evenly, then slowly drop the calcium hydroxide emulsion in step B-2 into it while stirring , the generated nano-titanium dioxide or nano-zinc oxide is coated on the surface of calcium phosphate. 6. The preparation method according to claim 3, characterized in that in step C, the drying temperature is 100°C, the calcination temperature is 300°C, and the calcination time is 0.5-2h.