CN117089255B

CN117089255B - Novel self-cleaning paint and preparation method thereof

Info

Publication number: CN117089255B
Application number: CN202311130415.6A
Authority: CN
Inventors: 周伟建; 黄理荣; 符传杰; 宋献军; 谢寅峰; 张旭
Original assignee: Guangdong Maydos Building Materials Co Ltd
Current assignee: Guangdong Maydos Building Materials Co Ltd
Priority date: 2023-09-04
Filing date: 2023-09-04
Publication date: 2025-08-08
Anticipated expiration: 2043-09-04
Also published as: CN117089255A

Abstract

本发明提供一种新型自清洁涂料，包括以下重量份的原料：丙烯酸乳液80～100份、二氧化钛复合材料5～10份、填料20～45份、水30～45份、助剂5～15份；该二氧化钛复合材料为纳米级二氧化钛材料，且该二氧化钛复合材料中掺杂有锰离子和镁离子。本发明提供的新型自清洁涂料制得的涂层具有优异的耐沾污性能，且自清洁能力强。The present invention provides a novel self-cleaning coating comprising the following raw materials in parts by weight: 80-100 parts of acrylic emulsion, 5-10 parts of titanium dioxide composite material, 20-45 parts of filler, 30-45 parts of water, and 5-15 parts of an additive. The titanium dioxide composite material is a nano-scale titanium dioxide material doped with manganese and magnesium ions. The coating produced from the novel self-cleaning coating has excellent stain resistance and strong self-cleaning ability.

Description

Novel self-cleaning paint and preparation method thereof

Technical Field

The invention relates to the technical field of coatings, in particular to a novel self-cleaning coating and a preparation method thereof.

Background

With the development of the age and the progress of technology, the modern building industry rapidly develops, and the requirements of people on the paint are also high in water and ship. The coating of the building exterior wall coating is exposed in the atmospheric environment, is subjected to natural environment changes such as wind blowing, sun drying, rain, sand dust, haze and the like, and is accompanied with serious environmental pollution, and dust and suspended pollutants in the atmosphere are more, so that the coating is more easy to be stained with stains, and the coating is easy to lose the original decorative effect for a long time.

Therefore, there is a need for a coating that provides a coating that has excellent stain resistance and a strong self-cleaning capability.

Disclosure of Invention

The invention aims to provide a novel self-cleaning coating and a preparation method thereof, so that the prepared coating has excellent stain resistance and strong self-cleaning capability.

According to one aspect of the invention, the novel self-cleaning coating comprises, by weight, 80-100 parts of acrylic emulsion, 5-10 parts of a titanium dioxide composite material, 20-45 parts of a filler, 30-45 parts of water and 5-15 parts of an auxiliary agent, wherein the titanium dioxide composite material is a nanoscale titanium dioxide material, and manganese ions and magnesium ions are doped in the titanium dioxide composite material.

According to the invention, the nanoscale titanium dioxide material is introduced into the coating, the super-hydrophilic effect of the titanium dioxide composite material under the action of illumination is utilized, so that the contact angle of a coating prepared from the novel self-cleaning coating can be reduced, water drops form a water film on the surface of the coating, and pollutants on the surface of the coating can be removed by the water film under the action of gravity, so that the self-cleaning effect is achieved. On the other hand, compared with the undoped nano-scale titanium dioxide, the titanium dioxide composite material doped with manganese ions and magnesium ions has better photocatalytic capability, can widen the photoresponse range and improves the quantum efficiency. When the titanium dioxide composite material in the coating is irradiated by light, the separation of electrons and holes is promoted, the positively charged holes oxidize organic molecules on the surface of the coating, and negatively charged electrons can be combined with oxygen in the external environment to form superoxide radicals, and the superoxide radicals attack the organic molecules on the surface of the coating. Therefore, by adding the titanium dioxide composite material into the coating, organic matters on the surface of the coating are converted into carbon dioxide and water, and the water can separate dirt on the surface of the coating from the coating, so that the effect of self-cleaning the coating is further achieved.

Preferably, the titanium dioxide composite is doped with divalent manganese ions and divalent magnesium ions.

The ionic radius of Ti ⁴⁺ is 60.5pm, the ionic radius of Mn ²⁺ is 67pm, and the ionic radii of the two are similar, so Mn ²⁺ can enter the titanium dioxide crystal lattice to be replaced by Ti ⁴⁺, and the excitation energy required by the transition of electrons and holes is greatly reduced. The ionic radius of Mg ²⁺ is 72pm, which is far larger than the radius of titanium ion, so that the possibility of replacing Ti ⁴⁺ with Mg ²⁺ is small, so that Mg ²⁺ can be uniformly dispersed on the surface of titanium dioxide, the growth of titanium dioxide crystals can be inhibited, the particle size distribution of the prepared titanium dioxide composite material is uniform, oxygen atoms in the titanium dioxide crystals can be promoted to be separated from the crystals, the generation of holes of the titanium dioxide composite material is accelerated, and the self-cleaning performance of the coating is improved. Therefore, the titanium dioxide is doped by adopting the divalent manganese ions and the divalent magnesium ions, so that the titanium dioxide composite material has excellent photocatalytic activity, and the coating prepared from the novel self-cleaning coating using the titanium dioxide composite material has excellent self-cleaning performance.

The titanium dioxide composite material is prepared by the steps of S1, uniformly mixing a titanium source material, a manganese source material, a magnesium source material, a dispersing auxiliary and a solvent to obtain a mixed solution, stirring the mixed solution to perform sol-gel reaction, standing the mixed solution to obtain gel, S2, drying the gel, and calcining the gel at 350-500 ℃ for 2-3 hours to obtain the titanium dioxide composite material.

Manganese ions and magnesium ions are uniformly mixed into titanium dioxide at a molecular level by a sol-gel method with mild conditions and simple procedures. And the titanium dioxide composite material with stable structure and uniform particle size is sintered by calcining at 350-500 ℃. If the calcining temperature is too high, the particle size distribution of the prepared titanium dioxide composite material is uneven, the titanium dioxide composite material is easy to accumulate locally after being introduced into the novel self-cleaning paint, the paint dispersibility is affected, and if the calcining temperature is too low, a completely grown crystal structure is difficult to obtain.

Preferably, in the mixed solution, manganese element is magnesium element is titanium element=0.1-0.2:0.05-0.1:1 according to the mole ratio.

When the doping amounts of the manganese element and the magnesium element meet the above relation, the prepared titanium dioxide composite material can enable the coating to have better self-cleaning performance. Because the valence states of Ti ⁴⁺ and Mn ²⁺ are not consistent, the number of substitutional Mn ²⁺ is limited. If the amount of the manganese source material to be charged is excessive, excessive manganese ions accumulate on the surface of the titanium dioxide composite material, and separation of electron-hole pairs is easily inhibited. If the amount of the manganese source material is too small, the doped manganese ions are too small, the photocatalytic performance of the titanium dioxide composite material is not obviously improved, and the self-cleaning performance of the coating is not easily improved greatly. Similarly, if too much magnesium source material is added, magnesium ions will accumulate on the surface of the titanium dioxide composite material in large amounts, thereby impeding the separation of electron-hole pairs. If the magnesium source material is too little, the regulation and control on the particle size distribution of the titanium dioxide composite material are not obvious enough.

Preferably, in the titanium dioxide composite material, manganese element, magnesium element, titanium element=0.14:0.07:1, calculated in terms of molar ratio.

Preferably, the pH value of the mixed solution is 1.5-2.5, and then the mixed solution is subjected to sol-gel reaction.

When the pH value of the mixed solution is 1.5-2.5, the mixed solution is easier to be converted into a gel state, and the titanium dioxide composite material with uniform particle size distribution is generated.

The acrylic emulsion comprises, by weight, 20-30 parts of acrylic monomers, 5-10 parts of functional monomers, 10-20 parts of organosilicon monomers, 2-8 parts of emulsifying agents and 80-100 parts of solvents, wherein the functional monomers are glycidyl methacrylate.

The inventor finds that after the titanium dioxide composite material is introduced into the novel self-cleaning paint, the coating has stronger self-cleaning performance, but is easy to cause yellowing after exposure. In order to reduce the yellowing risk of the coating, the inventor introduces glycidyl methacrylate into the acrylic emulsion, can promote the directional combination of acrylic monomers and the glycidyl methacrylate, ensures that the acrylic emulsion has stable structure and good compatibility with the titanium dioxide composite material. The novel self-cleaning coating prepared by the acrylic emulsion can reduce the yellowing probability of a coating prepared by the novel self-cleaning coating and improve the yellowing resistance of the coating.

The acrylic emulsion is preferably prepared by uniformly mixing an organosilicon monomer, an acrylic monomer, a functional monomer, an initiator, water and an emulsifier, and reacting the mixture at 70-90 ℃ for 3-5 hours to prepare the acrylic emulsion.

By adjusting the reaction temperature and the reaction time, the occurrence of side reactions can be reduced, and the shape of the final product can be controlled.

Preferably, the acrylic monomer consists of butyl acrylate and methyl methacrylate in a molar ratio of 2:1.

The acrylic monomer selected by the invention does not contain phenyl, phenolic aldehyde and other structures which are easy to yellow. And when the molar ratio of the butyl acrylate to the methyl methacrylate is 2:1, the acrylic monomer and the functional monomer are further crosslinked with each other, so that a three-dimensional network structure with stable structure is formed, and the yellowing resistance and the adhesion to a substrate of the coating are improved.

Preferably, the auxiliary agent comprises 0.5-2 parts of cellulose, 0.1-1 part of bactericide, 0.05-0.3 part of defoamer, 1-5 parts of glycol, 3-7 parts of film forming auxiliary agent and 0.1-1 part of thickener.

According to another aspect of the invention, a preparation method of the novel self-cleaning paint is provided, which comprises the following steps of uniformly mixing water, part of auxiliary agents and acrylic emulsion to obtain a paint intermediate, and uniformly mixing the paint intermediate with the rest of raw materials to obtain the novel self-cleaning paint.

The novel self-cleaning paint provided by the scheme has the advantages of simple preparation process steps, convenience in operation, mild conditions and good economic benefit.

Detailed Description

In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

Example 1

The embodiment provides a novel self-cleaning paint, which is prepared by the following specific steps:

(1) Preparation of titanium dioxide composite materials

The titanium dioxide composite material is a nanoscale titanium dioxide material, and Mn ²⁺ and Mg ²⁺ are doped in the titanium dioxide composite material.

The titanium dioxide composite material is prepared by the following steps:

S1, uniformly mixing a titanium source material, a dispersing aid and a solvent to obtain a dispersion liquid, and then sequentially dropwise adding a manganese source material and a magnesium source material into the dispersion liquid to obtain a mixed solution. In the mixed solution, the molar ratio of manganese element, magnesium element and titanium element is 0.14:0.07:1. Dropwise adding a nitric acid solution into the mixed solution to enable the pH value of the mixed solution to be 2, vigorously stirring for 30 minutes, enabling the mixed solution to carry out sol-gel reaction, and standing to obtain gel;

S2, drying the gel at 90 ℃ for 8 hours, and calcining at 450 ℃ for 2.5 hours to obtain the titanium dioxide composite material.

In the embodiment, butyl titanate is selected as a titanium source material, a MnSO ₄ solution with the concentration of 1mol/L is selected as a manganese source material, a MgSO ₄ solution with the concentration of 1mol/L is selected as a magnesium source material, absolute ethyl alcohol is selected as a solvent, and a dispersing auxiliary agent can be properly selected according to actual conditions.

(2) Preparation of acrylic emulsion

The raw materials for preparing the acrylic emulsion comprise 27 parts of acrylic monomer, 7 parts of functional monomer, 16 parts of organosilicon monomer, 5 parts of emulsifier and 90 parts of solvent. The acrylic monomer consists of butyl acrylate and methyl methacrylate according to a molar ratio of 2:1, and the functional monomer is glycidyl methacrylate.

The acrylic emulsion is prepared by uniformly mixing an organosilicon monomer, an acrylic monomer, a functional monomer, an initiator, water and an emulsifier, and reacting the mixture at 80 ℃ for 4 hours to prepare the acrylic emulsion.

(3) Preparation of novel self-cleaning paint

The novel self-cleaning paint is prepared from 90 parts of acrylic emulsion, 8 parts of titanium dioxide composite material, 32 parts of filler, 35 parts of water, 1 part of cellulose, 0.6 part of bactericide, 0.2 part of defoamer, 3 parts of glycol, 5 parts of film-forming auxiliary agent and 0.5 part of thickener.

The novel self-cleaning paint is prepared by uniformly mixing water, cellulose, bactericide, glycol and acrylic emulsion to obtain a paint intermediate, and uniformly mixing the paint intermediate with the rest raw materials to obtain the novel self-cleaning paint.

Example 2

This example, referring to the preparation method provided in example 1, a novel self-cleaning paint was prepared, and this example is different from example 1 in that the calcination temperature and calcination time were adjusted in S2 of the process of preparing the titanium dioxide composite material. In this example, calcination was carried out at 350 ℃ for 3 hours. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 3

This example, referring to the preparation method provided in example 1, a novel self-cleaning paint was prepared, and this example is different from example 1 in that the calcination temperature and calcination time were adjusted in S2 of the process of preparing the titanium dioxide composite material. In this example, calcination was carried out at 500 ℃ for 2 hours. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 4

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the titanium dioxide composite material, the feeding amounts of the titanium source material, the manganese source material and the magnesium source material are adjusted so that the molar ratio of manganese element, magnesium element and titanium element in the mixed solution is 0.05:0.03:1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 5

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the titanium dioxide composite material, the feeding amounts of the titanium source material, the manganese source material and the magnesium source material are adjusted so that the molar ratio of manganese element, magnesium element and titanium element in the mixed solution is 0.1:0.05:1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 6

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the titanium dioxide composite material, the feeding amounts of the titanium source material, the manganese source material and the magnesium source material are adjusted so that the molar ratio of manganese element, magnesium element and titanium element in the mixed solution is 0.2:0.1:1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 7

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the titanium dioxide composite material, the feeding amounts of the titanium source material, the manganese source material and the magnesium source material are adjusted so that the molar ratio of manganese element, magnesium element and titanium element in the mixed solution is 0.25:0.15:1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 8

This example, with reference to the preparation method provided in example 1, a novel self-cleaning coating was prepared, and this example was different from example 1 in that the pH of the mixed solution was made to be 1.5 during the preparation of the titanium dioxide composite material. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 9

This example, with reference to the preparation method provided in example 1, a novel self-cleaning coating was prepared, and this example was different from example 1 in that the pH of the mixed solution was made to be 2.5 during the preparation of the titanium dioxide composite material. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 10

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that the preparation step of the acrylic emulsion is omitted, and in the process of preparing the novel self-cleaning coating, the acrylic emulsion selected in the embodiment 1 is replaced by the commercial pure acrylic emulsion with equal quality. The commercial pure acrylic emulsion is a product with the brand A754 manufactured by Basoff company. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 11

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the acrylic emulsion, the molar ratio of butyl acrylate to methyl methacrylate in the acrylic monomer is 1:1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Example 12

The preparation method provided by the embodiment 1 is referred to in this embodiment to prepare a novel self-cleaning coating, and the difference between this embodiment and the embodiment 1 is that in the process of preparing the titanium dioxide composite material, the kind of manganese source material is adjusted, so that the titanium dioxide composite material is doped with Mn ⁴⁺ and Mg ²⁺. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Comparative example 1

The comparative example is different from example 1 in that the magnesium source material is omitted from the process of preparing the titanium dioxide composite material, and the prepared titanium dioxide composite material is not doped with magnesium element by referring to the preparation method provided in example 1. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Comparative example 2

The comparative example is different from example 1 in that the addition of the manganese source material is omitted in the process of preparing the titanium dioxide composite material, so that the prepared titanium dioxide composite material is not doped with manganese element. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Comparative example 3

The comparative example is prepared by referring to the preparation method provided in example 1, and the comparative example is different from example 1 in that the preparation of the titanium dioxide composite material is omitted, and in the process of preparing the novel self-cleaning coating, the titanium dioxide composite material selected in example 1 is replaced by the nano-grade anatase titanium dioxide which is equal in quality and commercially available. The proportions of the other raw materials and the preparation method are strictly consistent with those of the example 1.

Test case

The reference objects are the novel self-cleaning paint provided in examples 1-12 and comparative examples 1-3.

Test items:

(1) Storage stability referring to the test method for storage stability of paint of GB/T6753.3-1986, when a clear settled cake (corresponding to a settlement grade of 8) is detected, the time for the paint of the reference to appear to cake in storage is recorded.

(2) Self-cleaning performance referring to the test method in GB/T31815-2015 self-cleaning paint for building exterior surface, a 90-day outdoor rainwater stain test is carried out, and the self-cleaning performance of the coating prepared by each test object is tested.

(3) The yellowing resistance is measured by referring to the test method of artificial weathering exposure to fluorescent ultraviolet rays and water of GB/T23987-2009 color paint and varnish coatings, the coatings prepared by each reference object are placed in a fluorescent ultraviolet aging machine with irradiance of 0.68W/m ² and dry phase (without condensation) under the condition of (60+/-3) DEGC, continuous illumination is maintained for 168 hours all over, and after the illumination is finished, the coatings are taken out, and compared with the coating which is not illuminated, and the color change (delta E) is measured and recorded.

The test results are shown in Table 1.

TABLE 1 Performance test results from the test subjects

Analysis of results:

Comparing the coating corresponding to the novel self-cleaning coating prepared in the examples 1-12 with the coating prepared in the comparative examples 1-3, it can be shown that the coating corresponding to the examples 1-12 has higher self-cleaning performance, so that the titanium dioxide composite material doped with manganese ions and magnesium ions has better photocatalytic capability, and pollutants on the surface of the coating can be removed, thereby achieving the self-cleaning effect of the coating.

From the test performance corresponding to the coatings prepared in examples 1 to 3, it can be seen that, as the calcination temperature of the titanium dioxide composite material increases, the photocatalytic performance of the titanium dioxide composite material tends to increase and decrease, and the self-cleaning of the coating also tends to increase and decrease. From the test performances corresponding to examples 1 and 4-7, it can be seen that in the process of preparing the titanium dioxide composite material, the storage stability of the prepared coating and the self-cleaning performance of the corresponding coating all show a tendency of rising and then falling along with the rising of the proportion of manganese element and magnesium element in the mixed solution. Comparing the test performances corresponding to examples 1 and 8-9, it can be found that when the pH value of the mixed solution is 1.5-2.5, the mixed solution is easier to be converted into a gel state, and the titanium dioxide composite material with uniform particle size distribution is formed. Comparing the color differences corresponding to the coatings prepared in examples 1 and 10-11, it can be seen that the acrylic emulsion is used in the coatings prepared in examples 1 and 11, so that the yellowing risk of the coatings can be effectively reduced, and the adhesion of the coatings prepared in example 1 to the substrate is better than that of the coatings prepared in example 11. Comparing the test performance of the coatings prepared in example 1 with example 12, it was found that the titanium dioxide composite doped with Mn ²⁺ and Mg ²⁺ had better photocatalytic performance and the corresponding coating had better self-cleaning performance than the titanium dioxide composite doped with Mn ⁴⁺ and Mg ²⁺.

The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. The novel self-cleaning coating is characterized by comprising, by weight, 80-100 parts of acrylic emulsion, 5-10 parts of a titanium dioxide composite material, 20-45 parts of a filler, 30-45 parts of water and 5-15 parts of an auxiliary agent, wherein the titanium dioxide composite material is a nanoscale titanium dioxide material, and divalent manganese ions and divalent magnesium ions are doped in the titanium dioxide composite material;

The titanium dioxide composite material is prepared by the following steps:

S1, uniformly mixing a titanium source material, a manganese source material, a magnesium source material, a dispersing auxiliary and a solvent to obtain a mixed solution, stirring the mixed solution to perform sol-gel reaction, and standing to obtain gel;

S2, drying the gel, and calcining at 350-500 ℃ for 2-3 hours to obtain the titanium dioxide composite material.

2. The novel self-cleaning paint according to claim 1, wherein manganese element and titanium element are mixed in the mixed solution according to a molar ratio of 0.1-0.2:0.05-0.1:1.

3. The novel self-cleaning paint according to claim 1, wherein the pH of the mixed solution is set to 1.5 to 2.5, and the mixed solution is subjected to a sol-gel reaction.

4. The novel self-cleaning coating according to claim 1, wherein the acrylic emulsion comprises, by weight, 20-30 parts of acrylic monomers, 5-10 parts of functional monomers, 10-20 parts of organosilicon monomers, 2-8 parts of emulsifying agents and 80-100 parts of solvents, and the functional monomers are glycidyl methacrylate.

5. The novel self-cleaning paint as claimed in claim 4, wherein the acrylic emulsion is prepared by uniformly mixing the organosilicon monomer with the acrylic ester monomer, the functional monomer, the initiator, the water and the emulsifier, and reacting the mixture at 70-90 ℃ for 3-5 hours to prepare the acrylic emulsion.

6. The novel self-cleaning paint according to claim 4, wherein the acrylic monomer consists of butyl acrylate and methyl methacrylate according to a molar ratio of 2:1.

7. The novel self-cleaning paint as claimed in claim 1, wherein the auxiliary agent comprises 0.5-2 parts of cellulose, 0.1-1 part of bactericide, 0.05-0.3 part of defoamer, 1-5 parts of glycol, 3-7 parts of film-forming auxiliary agent and 0.1-1 part of thickener.

8. A method for preparing the novel self-cleaning paint according to any one of claims 1 to 7, which is characterized by comprising the steps of uniformly mixing water, part of the auxiliary agent and the acrylic emulsion to obtain a paint intermediate, and uniformly mixing the paint intermediate with the rest of raw materials to obtain the novel self-cleaning paint.