Aluminum coating film and preparation method thereof

Abstract

The invention discloses an aluminum coating film and a preparation method thereof, and relates to the field of aluminum coating film preparation, and the preparation method comprises the following steps: 1, adjusting the temperature of a water bath kettle to 70 DEG C, adding titanium dioxide slurry, and stirring until the temperature is uniform; 2, the temperature is kept at 70 DEG C, the initial pH value of the titanium dioxide slurry is 8-9, meanwhile, Al2 (SO4) 3 is added, and the pH value of the mixed slurry is adjusted to 6.0-6.5; thirdly, NaAlO2 and Al2 (SO4) 3 are added at the same time, the PH is kept to be 6.0-6.5, parallel flow is conducted, then the stirring speed is reduced, curing is conducted for 1-1.5 h, and mixed slurry is formed; according to the invention, the double-aluminum acidic coating is used for replacing a partial-aluminum alkaline coating, and acid and alkali are not used for adjusting the cocurrent flow pH value and the end point pH value in the cocurrent flow process, so that the production cost is saved, and the oil absorption amount of the product is reduced.

Description

Technical Field

[0001] The invention relates to the field of aluminum coating preparation, and in particular to an aluminum coating and a preparation method thereof. Background Art

[0002] Titanium dioxide is an important inorganic chemical pigment, the main component of which is titanium dioxide. There are two production processes for titanium dioxide: sulfuric acid process and chlorination process. It has important uses in industries such as coatings, inks, papermaking, plastics and rubber, chemical fibers, and ceramics.

[0003] The benefits of titanium dioxide aluminum coating mainly include improving weather resistance, reducing photocatalytic activity, enhancing dispersibility and compatibility, etc. Specifically:

[0004] First: Improve weather resistance: by coating a layer of aluminum oxide Al on the surface of titanium dioxide 2 O 3 , which can effectively improve the weather resistance of titanium dioxide, making it less likely to change color or powder when exposed to natural environments such as sunlight and rain for a long time.

[0005] Second: Reduce photocatalytic activity: Coating with alumina can reduce the photocatalytic activity of titanium dioxide and reduce damage to organic substrates. It is suitable for high weather resistance applications such as outdoor coatings, plastics, and automotive coatings.

[0006] Third: Enhanced dispersibility and compatibility: Coated alumina can enhance the dispersibility and compatibility of titanium dioxide in applications such as plastics and coatings, making it easier to disperse evenly in the application system and achieve better results.

[0007] Fourth: In addition, coated alumina can also improve the stability of titanium dioxide, extend its service life, and can be customized according to different needs to meet the requirements of various special application scenarios.

[0008] However, conventional coated alumina usually uses aluminum sulfate alkaline coating to coat titanium dioxide, but acids and alkalis are needed to adjust the parallel flow pH and endpoint pH during the parallel flow process, which is relatively costly and the oil absorption of the product needs to be improved.

[0009] Therefore, it is necessary to propose an aluminum coating and a preparation method thereof to solve the above problems. Summary of the invention

[0010] The purpose of the present invention is to provide an aluminum coating and a preparation method thereof, so as to solve the problem that conventional coated alumina usually uses aluminum sulfate alkaline coating to coat titanium dioxide, but during the parallel flow process, acid and alkali are needed to adjust the parallel flow pH and endpoint pH, which is relatively costly and the oil absorption of the product needs to be improved.

[0011] To achieve the above object, the present invention provides the following technical solution: a method for preparing an aluminum coating, comprising preparing a titanium dioxide slurry with a concentration of 300±10g / L, an Al 2 (SO 4 ) 3 , NaAlO with a concentration of 100±10g / L 2 ; comprising the following steps:

[0012] Step 1: Adjust the water bath temperature to 70°C, add titanium dioxide slurry, and stir until the temperature is uniform;

[0013] Step 2: Keep the temperature at 70°C, the initial pH of the titanium dioxide slurry is 8-9, and add Al 2 (SO 4 ) 3 , adjust the mixed slurry pH to 6.0-6.5;

[0014] Step 3: Add NaAlO 2 and Al 2 (SO 4 ) 3 , maintain pH=6.0-6.5, flow simultaneously, then reduce stirring speed and mature for 1-1.5h to form a mixed slurry;

[0015] Step 4: Wash and dry the coated slurry.

[0016] Preferably, the mixed slurry prepared by the aluminum coating preparation method is used to coat titanium dioxide.

[0017] Preferably, the titanium dioxide is coated with a double aluminate.

[0018] Preferably, a bialuminate coating is used instead of aluminate alkaline coating, and during the co-current process, no acid or alkali is used to adjust the co-current pH and the end point pH.

[0019] Preferably, the time of parallel flow in the third step is greater than 45 min and less than 90 min, and the NaAlO 2 and Al 2 (SO 4 ) 3 The flow ratio is 1.1-1.0:1, the unit is ml / min, and the pH is stable at 6-6.5.

[0020] The present invention also discloses an aluminum coating, which is prepared by the aluminum coating preparation method, wherein the components of the aluminum coating include titanium dioxide slurry, Al 2 (SO 4 ) 3 and NaAlO 2 .

[0021] Technical effects and advantages of the present invention:

[0022] 1. Use double aluminum acid coating instead of aluminum alkaline coating. No acid or alkali is used to adjust the parallel flow pH and end point pH during the parallel flow process, which saves production costs and reduces product oil absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the steps of the method for preparing the aluminum coating of the present invention. DETAILED DESCRIPTION

[0024] The present invention provides Figure 1 An aluminum coating and a preparation method thereof are shown;

[0025] Among them, the materials of aluminum coating include titanium dioxide slurry, Al 2 (SO 4 ) 3 、NaAlO 2 and H 2 SO 4 .

[0026] The concentration of titanium dioxide slurry is 300±10g / L; Al 2 (SO 4 ) 3 The concentration of NaAlO is 100±10g / L; 2 The concentration of H is 100±10g / L; 2 SO 4 The concentration is 100±10g / L; the concentration of NaOH is 250±10g / L.

[0027] There are two conventional methods for preparing aluminum coatings:

[0028] The first one: Al 2 (SO 4 ) 3 Encapsulation

[0029] The initial concentration of titanium dioxide slurry is 294.36 g / L, and the initial pH is 8.08; Al 2 (SO 4 ) 3 Concentration 108g / L; H 2 SO 4 Concentration: 98g / L; NaOH concentration: 250g / L (the concentration can also be prepared according to the actual test).

[0030] (1) Adjust the water bath temperature to 70°C, add 1 L of slurry, and stir until the temperature is uniform;

[0031] (2) Keep the temperature at 70°C, adjust the pH to 9.0-9.5, and add Al2 (SO 4 ) 3 and NaOH, then reduce the stirring speed and mature for 1h;

[0032] (3) Add H within 30 minutes 2 SO 4 Solution, adjust the slurry pH to about 6.0, keep warm for 30 minutes and then cool;

[0033] (4) Wash and dry the coated slurry.

[0034] The second type: NaAlO 2 Encapsulation

[0035] Titanium dioxide slurry concentration 294.36g / L, initial pH = 8.08, NaAlO 2 The concentration is 110g / L; H 2 SO 4 Concentration 106g / L.

[0036] (1) Adjust the temperature of the water bath to 70°C, add titanium dioxide slurry, and stir until the temperature is uniform;

[0037] (2) The temperature is maintained at 70°C, aluminum and sulfuric acid flow in parallel, and the pH is maintained at 9.0-9.5;

[0038] (3) Add H within 30 minutes 2 SO 4 Solution, adjust the slurry pH to about 6.0, keep warm for 30 minutes and then cool;

[0039] (4) Wash and dry the coated slurry.

[0040] The present invention provides a method for preparing an aluminum coating, wherein a mixed slurry is used to coat titanium dioxide, which is called double aluminum acid coating. The double aluminum acid coating is used instead of alumina or aluminum sulfate alkaline coating. During the parallel flow process, acid or alkali is not used to adjust the parallel flow pH and the end point pH, thereby saving production costs and reducing the oil absorption of the product.

[0041] The specific steps include:

[0042] Al 2 (SO 4 ) 3 -NaAlO 2 (Sodium aluminate) mixed coating

[0043] Step 1: Adjust the water bath temperature to 70°C, add titanium dioxide slurry, and stir until the temperature is uniform;

[0044] Step 2: Keep the temperature at 70℃, the initial pH of titanium dioxide slurry is 8-9, add Al 2(SO 4 ) 3 , adjust the mixed slurry pH to 6.0-6.5;

[0045] Step 3: Add NaAlO 2 and Al 2 (SO 4 ) 3 , maintain pH=6.0-6.5, the co-flow time is greater than 45min and less than 90min, then reduce the stirring speed and mature for 1-1.5h to form a mixed slurry;

[0046] Step 4: Wash and dry the coated slurry.

[0047] It should be noted that in the coating parallel flow, the laboratory has less material, so the parallel flow can be 45 minutes, while the production line has more material, usually 17-19 tons per pot, which requires 1.5 hours of parallel flow. Therefore, in actual operation, the parallel flow time can be adjusted according to the amount of material.

[0048] Correspondingly, the aging time can also be adjusted according to the amount of material.

[0049] Experimental conditions of the present invention:

[0050] According to NaAlO 2 Coating, Al 2 (SO 4 ) 3 Coating, Al 2 (SO 4 ) 3 -NaAlO 2 The mixed coating method was tested in multiple groups, and the experimental data were only briefly introduced and no longer made public; for example: 2 (SO 4 ) 3 Four experiments were prepared in the encapsulation method, one of which was Al 2 (SO 4 ) 3 The membrane was washed overnight; then NaAlO 2 、Al 2 O 3 Encapsulation volume, parallel flow H 2 SO 4 amount, amount of NaOH added, H used to adjust the end point pH 2 SO 4 Quantity statistics in the form of tables.

[0051] In Al 2 (SO 4 ) 3-Three groups of experiments were prepared for the mixed coating of aluminum, respectively, to test the slurry amount, initial pH, aluminum addition amount / addition flow rate, aluminum sulfate addition amount / addition flow rate, coating process pH, and end point H 2 SO 4 The added amount and the total amount of alumina coating are tabulated.

[0052] Experimental data:

[0053] After the experiment, NaAlO was tested 2 Coating, Al 2 (SO 4 ) 3 Coating and Al 2 (SO 4 ) 3 - Trace indicators of aluminum mixed coating (including SiO 2 Percentage, Al 2 O 3 Percentage and Fe 2 O 3 percentage), color index (including △L, △b, dispersion power, tinting power, oil absorption and finished product PH)

[0054] Among them, △L means white, △b means yellow, and both △L and △b are the whiteness of the oil phase (relative to the standard sample value).

[0055] in conclusion:

[0056] 1. Pack Al 2 O 3 Temperature has a great influence on the whiteness and dispersion index of titanium dioxide. 2 O 3 The effect is not as good as high temperature Al 2 O 3 The effect is good, but it contains Al 2 O 3 The temperature should not be too high, otherwise the performance of titanium dioxide will be reduced. The coating temperature should be controlled at 70-80℃. 2 (SO 4 ) 3 After overnight washing, the decolorization value of the coated sample increased, but had little effect on other indicators; Al 2 (SO 4 ) 3 Coating for more than 45 minutes has little effect on the Al retention rate of the sample.

[0057] 2.Al 2 (SO 4 ) 3 -NaAlO 2 The Al retention rate of mixed coating under acidic conditions is higher than that under alkaline conditions. 2 (SO4 ) 3 With NaAlO 2 When the double aluminum coating speed is the same, the Al retention rate reaches 80% (the fluorescence instrument test data of each manufacturer has a certain deviation from the theory), which is about 10% higher than that under alkaline conditions.

[0058] 3. Compared with the single aluminum source coating, the △L and △b values ​​of the mixed aluminum source coating samples increased, the oil absorption decreased, and the scattering power was equivalent.

Claims

1. A method for preparing an aluminum coating, comprising preparing a titanium dioxide slurry with a concentration of 300±10 g / L, an Al2(SO4)3 with a concentration of 100±10 g / L, and a NaAlO2 with a concentration of 100±10 g / L; characterized in that: The following steps are involved: Step 1: Adjust the water bath temperature to 70°C, add titanium dioxide slurry, and stir until the temperature is uniform; Step 2: Keep the temperature at 70°C, the initial pH of the titanium dioxide slurry is 8-9, and add Al2(SO4)3 to adjust the mixed slurry pH to 6.0-6.5; Step 3: Add NaAlO2 and Al2(SO4)3 simultaneously, keep pH=6.0-6.5, flow in parallel, then reduce stirring speed and ripen for 1-1.5h to form a mixed slurry; Step 4: Wash and dry the coated slurry.

2. The method for preparing an aluminum coating according to claim 1, characterized in that: The mixed slurry prepared by the aluminum coating preparation method is used for coating titanium dioxide.

3. The method for preparing an aluminum coating according to claim 2, characterized in that: The method of including titanium dioxide is double aluminum acid coating.

4. The method for preparing an aluminum coating according to claim 3, characterized in that: A bialuminate acidic membrane is used to replace aluminate alkaline membrane, and during the parallel flow process, no acid or alkali is used to adjust the parallel flow pH and the end point pH.

5. The method for preparing an aluminum coating according to claim 1, characterized in that: In the third step, the parallel flow time is greater than 45 minutes and less than 90 minutes. During the parallel flow, the flow ratio of NaAlO2 and Al2(SO4)3 is controlled to be 1.1-1.0:1, in ml / min, and the pH is stabilized at 6-6.

5.

6. An aluminum coating, characterized in that: The aluminum coating is prepared by the method for preparing an aluminum coating as described in any one of claims 1 to 5, wherein the components of the aluminum coating include titanium dioxide slurry, Al2(SO4)3 and NaAlO2.

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