A kind of super-wetting titanium dioxide based on coacervate and its preparation method and application

Abstract

The application discloses a kind of based on condensate's super wetting titanium dioxide and its preparation method and application, belong to nanometer material technical field.The preparation method of based on condensate's super wetting titanium dioxide of the application, including the following steps: inorganic coated titanium dioxide is added into sodium polyacrylate solution, carries out first stirring reaction, then polyacrylamide solution or polymethyl methacryloyl oxyethyl trimethyl ammonium chloride solution is added, carries out second stirring reaction, takes condensate phase and carries out drying after crushing, obtains based on condensate's super wetting titanium dioxide.The super wetting titanium dioxide based on condensate prepared by the application shows super wetting (contact angle is 0 °, namely presents super wetting to hydrophobic and hydrophilic surface) to solvent such as low surface tension n-hexane to high surface tension water.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a superwetting titanium dioxide based on aggregates, its preparation method, and its applications. Background Technology

[0002] Titanium dioxide is a white, non-toxic inorganic filler with high hiding power, often added as a white pigment to materials such as coatings, plastics, rubber, fabrics, inks, ceramics, separation membranes, pharmaceuticals, and cosmetics. However, titanium dioxide is characterized by high photocatalytic activity, easy yellowing, and agglomeration. Therefore, organic coating methods are often used to improve the weather resistance of titanium dioxide and its wettability with plastic substrates.

[0003] Currently used organic coating agents include 2-phosphono-2-hydroxy-1,1-oxalic acid and its derivatives, 3-aminopropyltriethoxysilane, trimethylolpropane, oligoethylene glycol, oligoglycerol and its derivatives, etc. The interactions between titanium dioxide and the substrate are weak interactions such as van der Waals forces and hydrogen bonds. These cannot effectively solve the problems of poor dispersibility and wettability of titanium dioxide, and they are often not suitable for substrates with different structures (such as PE, PP, PS, PET and polyamide with different surface tensions and compatibility). As a result, titanium dioxide still has problems such as agglomeration, stress concentration and decreased tensile strength.

[0004] Therefore, how to solve the interfacial wettability problem between titanium dioxide and substrates with different surface tensions, thereby improving the whiteness, weather resistance, mechanical properties, and corrosion resistance of the material, and reducing the material preparation cost, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a superwetting titanium dioxide based on aggregates, its preparation method, and its application, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of the present invention: a method for preparing superwetting titanium dioxide based on aggregates, comprising the following steps:

[0008] Inorganic coated titanium dioxide is added to sodium polyacrylate solution for a first stirring reaction. Then, polyacrylamide solution or polymethacryloyloxyethyltrimethylammonium chloride solution is added for a second stirring reaction. The aggregate phase is dried and then pulverized to obtain the aggregate-based superwetting titanium dioxide.

[0009] Preferably, the inorganic coated titanium dioxide includes titanium dioxide coated with Al2O3 and SiO2.

[0010] Preferably, the mass of the Al2O3 is 3-5% of the mass of the inorganically coated titanium dioxide, more preferably 3.61%;

[0011] The mass of SiO2 is 1 to 2.5% of the mass of the inorganically coated titanium dioxide, more preferably 1.55%;

[0012] The diameter of the titanium dioxide is 200-300 nm.

[0013] More preferably, the titanium dioxide includes rutile titanium dioxide.

[0014] Preferably, the concentration of the sodium polyacrylate solution is 5-10 wt%.

[0015] The concentration of the polyacrylamide solution is 5-10 wt%.

[0016] The concentration of the polymethacryloyloxyethyltrimethylammonium chloride solution is 5–10 wt%.

[0017] Preferably, when the substance added after the first stirring reaction is a polyacrylamide solution, the total mass of sodium polyacrylate in the sodium polyacrylate solution and polyacrylamide in the polyacrylamide solution is 0.5 to 7% of the mass of the inorganically coated titanium dioxide.

[0018] More preferably, the solvents in the sodium polyacrylate solution and the polyacrylamide solution are both aqueous solutions with a pH of 5 to 10, and the pH of the solution is adjusted by hydrochloric acid and sodium hydroxide solution.

[0019] Preferably, the molecular weight of the sodium polyacrylate is 4000-6000 g / mol;

[0020] The polyacrylamide has a molecular weight of 5000-8000 g / mol and an ionic degree of 20-50%.

[0021] More preferably, the polyacrylamide is one of anionic polyacrylamide, neutral polyacrylamide, and cationic polyacrylamide.

[0022] Preferably, the mass of the sodium polyacrylate is 20-60% of the total mass of sodium polyacrylate and polyacrylamide.

[0023] Preferably, the first stirring reaction time is 0.5 to 1 hour;

[0024] The second stirring reaction takes 0.5 to 2 hours.

[0025] When the two polymers (sodium polyacrylate and polyacrylamide) are mixed, they separate into a cohesive phase and a supernatant. The cohesive phase is a viscous solid at the bottom, containing a complex of polyacrylate and polyacrylamide, and coating titanium dioxide. Inorganic counterions from both polymers are expelled (driven by entropy increase) into the supernatant. Sodium polyacrylate accounts for 20–60% of the total mass of the organic coating agents (sodium polyacrylate and polyacrylamide). A suitable ratio of sodium polyacrylate to polyacrylamide (20–60% : 40–80%) must be maintained; otherwise, the polymers will enter the supernatant, and inorganic ions will not be effectively expelled from the cohesive phase.

[0026] The aggregate formed by the composite of two polymers (sodium polyacrylate and polyacrylamide) used in this invention can reduce surface energy through the discontinuous micro-regions of its polar (ionic region) and non-polar (polymer skeleton), resulting in stronger wettability and adhesion to both polar and non-polar surfaces. While efficiently dispersing titanium dioxide, the two polymers also enable the prepared superwetting titanium dioxide to exhibit superwetting properties on surfaces of different polarities, thereby improving the interfacial force between the superwetting titanium dioxide and the polymer substrate, resulting in better dispersion. Compared with commercially available organic-coated titanium dioxide, it shows significant advantages in whiteness and mechanical properties.

[0027] The second technical solution of the present invention: a superwetting titanium dioxide based on aggregates prepared by the above preparation method.

[0028] The third technical solution of the present invention: the application of the above-mentioned superwetting titanium dioxide based on aggregates in the preparation of plastics, fibers, rubber, coatings, inks, paper, cosmetics, separation films or pharmaceuticals.

[0029] The present invention discloses the following technical effects:

[0030] (1) The superwetting titanium dioxide based on aggregates prepared in this invention exhibits superwetting properties (contact angle of 0°, i.e., superwetting properties on both hydrophobic and hydrophilic surfaces) to solvents ranging from low surface tension n-hexane to high surface tension water. This indicates that the superwetting titanium dioxide prepared in this invention has the potential to be applied to different plastic substrates and exhibits good wettability and applicability to different plastic substrates, which can make up for the shortcomings of existing titanium dioxide.

[0031] (2) The present invention uses a new combination of organic coating agents (sodium polyacrylate and polyacrylamide) based on composite aggregates to organically coat titanium dioxide, so that the titanium dioxide coating is dispersed in the organic coating agent, thereby improving the wettability of titanium dioxide to different substrates.

[0032] The composite aggregate is formed by combining sodium polyacrylate and polyacrylamide. The main interaction between the aggregates is electrostatic interaction, combined with multiple hydrogen bonds and van der Waals forces, forming a low surface tension phase.

[0033] (3) Compared with existing titanium dioxide-doped plastic composites, the titanium dioxide-doped plastic composites prepared by the present invention based on aggregate-based super-wetting titanium dioxide have more uniform dispersion of titanium dioxide, resulting in better mechanical properties and higher whiteness values.

[0034] (4) The preparation method of the present invention has simpler equipment requirements, milder processing conditions, lower process and raw material costs, and does not use small molecule organic matter, resulting in no VOC pollution, while exhibiting significant performance advantages. In addition, due to the high compatibility of the aggregate structure with guest molecules (i.e., dyes and inorganic and organic nanoparticles, etc.), it can enrich and retain high concentrations of dye molecules, antibacterial components, etc., providing a carrier for further functionalization of titanium dioxide. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 The contact angles of the superwetting titanium dioxide film prepared for Example 1 with solvents of different polarities are shown, where (A) is water and (B) is n-hexane.

[0037] Figure 2 The characterization results of titanium dioxide doped with PVC1 and titanium dioxide doped with PVC2 prepared for Example 2 are shown in the figure. (A) is a cross-sectional SEM image of titanium dioxide doped with PVC1, (B) is an EDS elemental distribution map of titanium dioxide doped with PVC1, (C) is a cross-sectional SEM image of titanium dioxide doped with PVC2, and (D) is an EDS elemental distribution map of titanium dioxide doped with PVC2.

[0038] Figure 3 The mechanical properties and whiteness values ​​of the PVC, PVC-TiO2-1 and PVC-TiO2-2 sheets prepared for Example 3 are shown in the figure. (A) represents Young's modulus, (B) represents tensile strength, (C) represents elongation at break, and (D) represents whiteness value. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0045] Example 1

[0046] A method for preparing superwetting titanium dioxide based on aggregates:

[0047] (1) The inorganic coated titanium dioxide was provided by Dawn Titanium Industry and was coated with Al2O3 and SiO2; the titanium dioxide was rutile titanium dioxide with a diameter of 200-300 nm.

[0048] The mass of Al2O3 is 3.61% of the mass of inorganically coated titanium dioxide;

[0049] The mass of SiO2 is 1.55% of the mass of the inorganically coated titanium dioxide.

[0050] (2) Sodium polyacrylate (molecular weight of 4000-6000 g / mol) was added to deionized water with pH 7 to obtain a sodium polyacrylate aqueous solution with a concentration of 5 wt%.

[0051] Polyacrylamide (cationic type, molecular weight 5000-8000 g / mol, ionicity 30%) was added to deionized water at pH 7 to obtain a 5 wt% polyacrylamide aqueous solution.

[0052] Inorganic-coated titanium dioxide was added to a 5 wt% sodium polyacrylate aqueous solution and stirred vigorously (500 rpm / min) for 1 h. Then, under stirring conditions (500 rpm / min), a 5 wt% polyacrylamide aqueous solution was added, and stirring was continued for 0.5 h (500 rpm / min) until large viscous agglomerates appeared at the bottom and the supernatant became clear. The supernatant was poured off, and the lower viscous agglomerates were washed twice with water, dried, and pulverized to obtain superwetting titanium dioxide based on agglomerates.

[0053] The total mass of sodium polyacrylate in the sodium polyacrylate solution and polyacrylamide in the polyacrylamide solution is 5% of the mass of the inorganically coated titanium dioxide.

[0054] The mass ratio of sodium polyacrylate in the sodium polyacrylate solution to polyacrylamide in the polyacrylamide solution is 46:54.

[0055] Example of effect 1

[0056] The superwetting titanium dioxide based on aggregates prepared in Example 1 was pressed into a film using a flat vulcanizing machine (pressed at room temperature for 10 minutes under 10 MPa pressure) to obtain a superwetting titanium dioxide film. The contact angles of the superwetting titanium dioxide film with solvents of different polarities (i.e., solvents with different surface tensions) were then tested. The results are shown in Table 1 and... Figure 1 .

[0057] Figure 1 Figure (A) shows the contact angle of water on the surface of the superwetted titanium dioxide film, and Figure (B) shows the contact angle of n-hexane on the surface of the superwetted titanium dioxide film.

[0058] Table 1. Contact angles of superwetting titanium dioxide films to solvents of different polarities (20℃)

[0059]

[0060] from Figure 1 As can be seen, the contact angles of water and n-hexane on the surface of the superwetted titanium dioxide film are both 0°.

[0061] As can be seen from Table 1, the superwetting titanium dioxide film exhibits superwetting properties (contact angle of 0°) in solvents ranging from low surface tension hexane to high surface tension water.

[0062] Example 2

[0063] Comparative titanium dioxide (Dawn Titanium Industry R-3195, which uses the same inorganic coated titanium dioxide as super-wetted titanium dioxide, but uses a small molecule organic coating agent) and PVC (the mass of the comparative titanium dioxide is 3% of the mass of PVC) were mixed, extruded and granulated using a twin-screw extruder (extrusion granulation conditions: 150℃ in zone 1, 170℃ in zone 2, 180℃ in zone 3, 180℃ in zone 1 of the die head, 180℃ in zone 2 of the die head, cylindrical particles 2mm (diameter) × 4mm (column length)) to obtain titanium dioxide doped with PVC1.

[0064] The super-wetting titanium dioxide based on aggregates prepared in Example 1 was mixed with PVC (the mass of the super-wetting titanium dioxide was 3% of the mass of PVC), and then extruded and granulated using a twin-screw extruder (extrusion granulation conditions: zone 1 150°C, zone 2 170°C, zone 3 180°C, die head zone 1 180°C, die head zone 2 180°C, cylindrical particles 2mm (diameter) × 4mm (column length)) to obtain titanium dioxide doped with PVC2.

[0065] The dispersion of titanium dioxide and the aggregate-based superwetting titanium dioxide prepared in Example 1 in PVC substrates was analyzed and compared. The results are shown in the figure. Figure 2 .

[0066] Figure 2 Figure (A) is a cross-sectional SEM image of titanium dioxide doped with PVC1, Figure (B) is an EDS elemental distribution map of titanium dioxide doped with PVC1, Figure (C) is a cross-sectional SEM image of titanium dioxide doped with PVC2, and Figure (D) is an EDS elemental distribution map of titanium dioxide doped with PVC2.

[0067] Figure 2 The green color in diagrams (B) and (D) represents titanium dioxide.

[0068] from Figure 2 As can be seen, incorporating the superwetting titanium dioxide based on aggregates prepared in Example 1 into the PVC substrate can make the titanium dioxide dispersed individually, and the dispersibility is significantly improved compared with the control titanium dioxide.

[0069] Example 3

[0070] PVC substrate, PVC doped with comparative titanium dioxide (i.e., titanium dioxide-doped PVC1), and PVC doped with aggregate-based superwetting titanium dioxide (i.e., titanium dioxide-doped PVC2) were respectively pressed into sheets using a flat vulcanizing machine (pressed at 170℃ for 5 minutes under 10MPa pressure, thickness 3.4mm). The resulting sheets were PVC, PVC-TiO2-1, and PVC-TiO2-2. Tensile properties and whiteness were tested according to ISO 527-2:2019 standard. The results are shown in [Figure number missing]. Figure 3 .

[0071] Figure 3 In the figure, (A) represents Young's modulus, (B) represents tensile strength, (C) represents elongation at break, and (D) represents whiteness value.

[0072] from Figure 3 As can be seen, the Young's modulus, tensile strength, elongation at break, and whiteness of PVC doped with aggregate-based superwetting titanium dioxide (PVC-TiO2-2) are significantly superior to those of PVC doped with comparative titanium dioxide (PVC-TiO2-1). This further demonstrates that the aggregate-based superwetting titanium dioxide prepared in Example 1 has better interfacial wettability and dispersibility with PVC, thus exhibiting significant performance advantages.

[0073] Example 2

[0074] Same as Example 1, except that the 5 wt% polyacrylamide aqueous solution was replaced with a 5 wt% polymethacryloyloxyethyltrimethylammonium chloride solution; thus, superwetting titanium dioxide based on aggregates was prepared.

[0075] The superwetting titanium dioxide based on aggregates prepared in this embodiment was used to prepare a superwetting titanium dioxide film, and the same solvent contact angle test as in Table 1 was performed, and the contact angle was 0° for all films.

[0076] Comparative Example 1

[0077] Same as Example 1, except that the 5 wt% polyacrylamide aqueous solution was replaced with a 5 wt% polyallylamine hydrochloride solution. Precipitation formed; aggregates could not be formed.

[0078] Comparative Example 2

[0079] Same as Example 1, except that the 5 wt% sodium polyacrylate aqueous solution was replaced with a 5 wt% polyvinyl alcohol solution. No aggregates could form.

[0080] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing superwetting titanium dioxide based on aggregates, characterized in that, Includes the following steps: Inorganic coated titanium dioxide is added to sodium polyacrylate solution for a first stirring reaction, followed by the addition of polyacrylamide solution for a second stirring reaction. The aggregated phase is then dried and pulverized to obtain the aggregate-based superwetting titanium dioxide. Sodium polyacrylate accounts for 20-60% of the total mass of sodium polyacrylate and polyacrylamide, and the ratio of sodium polyacrylate to polyacrylamide is 20-60%:40-80%.

2. The preparation method according to claim 1, characterized in that, The inorganic-coated titanium dioxide includes titanium dioxide coated with Al2O3 and SiO2.

3. The preparation method according to claim 2, characterized in that, The mass of the Al2O3 is 3-5% of the mass of the inorganically coated titanium dioxide; The mass of SiO2 is 1-2.5% of the mass of the inorganically coated titanium dioxide; The diameter of the titanium dioxide is 200~300 nm.

4. The preparation method according to claim 1, characterized in that, The concentration of the sodium polyacrylate solution is 5-10 wt%. The concentration of the polyacrylamide solution is 5~10 wt%.

5. The preparation method according to claim 1, characterized in that, The total mass of sodium polyacrylate in the sodium polyacrylate solution and polyacrylamide in the polyacrylamide solution is 0.5-7% of the mass of the inorganically coated titanium dioxide.

6. The preparation method according to claim 5, characterized in that, The molecular weight of the sodium polyacrylate is 4000~6000 g / mol; The polyacrylamide has a molecular weight of 5000~8000 g / mol and an ionicity of 20~50%.

7. The preparation method according to claim 1, characterized in that, The first stirring reaction takes 0.5 to 1 hour; The second stirring reaction takes 0.5 to 2 hours.

8. A superwetting titanium dioxide based on aggregates prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the aggregate-based superwetting titanium dioxide of claim 8 in the preparation of plastics, fibers, rubber, coatings, inks, paper, cosmetics or separation films.

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