Daytime passive radiation refrigeration polyurea composite spraying material with structure repairing function and preparation method thereof

Abstract

The invention belongs to the technical field of repairing refrigeration spraying materials, and particularly discloses a daytime passive radiation refrigeration polyurea composite spraying material with a structure repairing function and a preparation method of the daytime passive radiation refrigeration polyurea composite spraying material. And preparing the spraying material with certain flowability. The porous composite polyurea repairing radiation refrigeration spraying material is synthesized by utilizing the multi-graded micron hollow glass beads, has a multi-stage pore structure, and can optimize the pore size grading, so that the spraying material has high daytime radiation refrigeration power and excellent structure repairing capability at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of repairing refrigeration spraying materials, and particularly relates to a daytime passive radiative cooling polyurea composite spraying material with a structure repairing function and a preparation method thereof. Background Art

[0002] The plateau region is the engine of western development. However, due to the large temperature difference between day and night and severe ultraviolet radiation in the plateau region, the excessive temperature difference between the inside and outside of the building structure caused by exposure to the sun and uneven heating generate large thermal stresses, resulting in frequent cracking on the surface of the structure, reducing the durability of the structure, and seriously restricting the high-quality and sustainable development of plateau infrastructure construction. Therefore, strengthening and repairing the cracks on the surface of the structure is the key to ensuring its long-term safe operation. The in-situ spraying method is a common means of repairing cracks, which specifically refers to spraying a repair material at the crack to build a protective layer. Existing structural repair spraying materials mainly include cement mortar, epoxy resin, polyurethane, and polyurea, etc. However, the surface of the repaired structure will still be unevenly heated under the action of sunlight, leading to secondary cracking.

[0003] Daytime radiative cooling materials are a type of zero-energy-consuming repair and refrigeration materials. It can use its own surface structure to reflect more than 90% of sunlight, inhibit solar radiation heating, and at the same time transfer its own heat to the extremely cold outer space (3K) in the form of long-wave infrared radiation heat transfer through the atmospheric transparent window (8 - 13μm), thereby reducing its own temperature to achieve the purpose of refrigeration. Therefore, preparing a radiative cooling material with a structure repairing function can significantly reduce the thermal stress accumulation at the repair under sunlight, fundamentally prevent the structure from cracking again, and this is an urgent problem to be solved at present. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a daytime passive radiative cooling polyurea composite spraying material with a structure repairing function and a preparation method thereof. The polyurea composite material provided by the present invention has the characteristics of light weight, high strength, good durability, and excellent radiative cooling performance, and can be applied to the surface of buildings by means of high-pressure airless spraying or brushing. While repairing and strengthening the cracks on the surface of the structure, it can also reduce the structure temperature at the repair under sunlight, significantly reduce the thermal stress accumulation, and the long-term repair effect is more guaranteed, solving the problems mentioned in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A daytime passive radiative cooling polyurea composite spraying material with a structure repair function, the composite spraying material comprising a polyurea A component, a B component, multi-graded hollow glass microspheres, and metal oxide powder, wherein the A component comprises the following raw materials in parts by weight: 31-55 parts of isocyanate, 45-69 parts of polyol, 2-10 parts of silane coupling agent; the B component comprises the following raw materials in parts by weight: 40-80 parts of polyaspartic acid ester resin, 2-5 parts of defoaming agent, 1-6 parts of leveling agent, 1-5 parts of antioxidant.

[0006] Preferably, the solar reflectance of the composite spraying material is not less than 95%; the long-wave infrared emissivity is not less than 93%; the flexural strength is not less than 25 MPa, and the compressive strength is not less than 60 Mpa; the porosity is 50%-80%.

[0007] On the other hand, to achieve the above object, the present invention also provides the following technical solution: A preparation method of a daytime passive radiative cooling polyurea composite spraying material with a structure repair function, comprising the following steps:

[0008] S1. Prepare the polyurea A component material: Weigh the polyol in proportion, add the polyol to a reaction vessel and start stirring; then heat to 105-115 °C; evacuate to remove the moisture in the raw materials; cool the liquid material temperature to 50-60 °C; weigh the isocyanate in proportion, add the isocyanate to the reaction vessel and stir for 0.5-1 hour, slowly raise the temperature to 80-90 °C and react for 2-3 hours, and detect the NCO value; when the NCO value reaches the designed value of 98-105%, weigh the silane coupling agent in proportion and add it to the reaction vessel, keep the temperature at 0.5-60 °C, and discharge to obtain the polyurea A component material;

[0009] S2. Prepare the B component material: Weigh the polyaspartic acid ester resin and antioxidant in proportion, add them to a vacuum stirring reaction vessel and start stirring, raise the temperature of the liquid material to 105-115 °C; add the pigment filler to the vacuum stirring reaction vessel and stir for 0.5 hour; maintain the temperature at 105-115 °C, evacuate to remove the moisture in the raw materials; add the defoaming agent and leveling agent in proportion and stir for 0.5 hour; cool to 50-60 °C and discharge to obtain the B component material;

[0010] S3. Add the polyurea A component to the metal oxide and micron hollow glass microspheres and mix evenly to obtain a mixed dry powder;

[0011] S4. Add the B component material to the mixed dry powder in step S3, and mix evenly to obtain the composite spraying material.

[0012] Preferably, in step S1 and step S2, the dehydration after vacuum pumping is specifically as follows: vacuum pump to -0.1 to -0.09 Mpa to dehydrate and remove the moisture in the raw materials until the moisture content of the raw materials drops below five ten-thousandths.

[0013] Preferably, in step S3, it specifically includes the following:

[0014] S31. Dry the metal oxide powder and the micron hollow glass microspheres;

[0015] S32. Mix the dried metal oxide powder and the micron hollow glass microspheres;

[0016] S33. Add the polyurea component A to the dry powder after mixing in step S32 and stir to obtain a mixed dry powder.

[0017] Preferably, in step S32, the mass ratio of the micron hollow glass microspheres to the metal oxide is 0.25 - 1; in step S33, the mass ratio of the polyurea component A to the dry powder after mixing is 0.2 - 1.

[0018] Preferably, the micron hollow glass microspheres are selected from one or a mixture of more than one with a particle size of 2 μm - 50 μm.

[0019] Preferably, the metal oxide is one or more of powdery Al2O3, TiO2, MgO, CaCO3, ZnO, ZrO2.

[0020] The beneficial effects of the present invention are:

[0021] 1) The hollow glass microspheres and metal oxide powder added in the spraying material of the present invention can selectively emit long-wave infrared emissivity while maintaining a very high solar reflectivity, enabling the material to have excellent radiative cooling effect while being lightweight and high-strength; and the polyaspartic acid ester polyurea added to the material plays a strong repair role for building materials;

[0022] 2) The present invention uses multi-graded micron hollow glass microspheres to synthesize a porous composite spraying material, which has a multi-porous structure and can optimize the pore size grading, enabling the polyurea composite material to have both high daytime radiative cooling power and high mechanical strength while taking into account the repair effect;

[0023] 3) The polyurea material provided by the present invention contains a large number of urea bonds (NH-CO-NH) and ether bonds (O) in its molecular structure. The ether bond and the lone pair of electrons on the nitrogen atom (N-H) can form hydrogen bonds, thereby enhancing the intermolecular interaction force of the polyurea. At the same time, the urea bond has a relatively large polarity and the molecule has a relatively strong polarity, which also enhances the intermolecular interaction force. The strong intermolecular interaction can effectively prevent water molecules from infiltrating, making the material have strong hydrophobicity, and the wetting angle of the material is 95-125°. Furthermore, the polyurea composite material of the present invention has hydrophobic characteristics, can prevent the accumulation of pollutants such as dust, and achieves a self-cleaning effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the surface of a structure to be repaired coated with a polyurea composite spraying material with structural repair function and daytime passive radiative cooling;

[0025] Figure 2 Schematic diagram of the preparation process of a polyurea composite spraying material with structural repair function and daytime passive radiative cooling;

[0026] Figure 3 Schematic diagram of the process of adding component A of polyurea to metal oxides and micron hollow glass microspheres. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment 1

[0029] The present invention provides a technical solution: a polyurea composite spraying material with structural repair function and daytime passive radiative cooling, the composite spraying material includes component A of polyurea, component B, multi-graded hollow glass microspheres and metal oxide powder, wherein, component A includes the following raw materials in parts by weight: 31-55 parts of isocyanate, 45-69 parts of polyol, 2-10 parts of silane coupling agent; component B includes the following raw materials in parts by weight: 40-80 parts of polyaspartate resin, 2-5 parts of defoaming agent, 1-6 parts of leveling agent, 1-5 parts of antioxidant.

[0030] The solar reflectivity of the composite spraying material is not less than 95%; the long-wave infrared emissivity is not less than 93%; the flexural strength is not less than 25 MPa, and the compressive strength is not less than 60 Mpa; the porosity is 50%-80%.

[0031] The above composite spraying material is applied to the surface of the structure to be repaired by high-pressure airless spraying or brushing, and left to stand to cure into a film, as Figure 1 shown. The surface to be repaired can be wood, concrete, tiles, glass, metal, and plastic; or, the surface of the main body to be repaired, where the main body is infrastructure such as bridges, roads, dams, industrial and civil buildings, etc.

[0032] Example 2

[0033] As Figure 2 shown, Figure 2 is a schematic diagram of the manufacturing process of the daytime passive radiative cooling polyurea composite spraying material with a structure repair function in an embodiment of the present invention. The preparation method includes the following steps:

[0034] S1. Prepare the polyurea component A material: Weigh the polyol according to the proportion, add the polyol to the reaction vessel and start stirring; then heat to 105 - 115°C; evacuate to -0.1 to -0.09 Mpa to remove the moisture in the raw materials until the moisture content of the raw materials drops below five ten-thousandths; cool the liquid material temperature to 50 - 60°C; weigh the isocyanate according to the proportion, add the isocyanate to the reaction vessel and stir for 0.5 - 1 hour, slowly heat up to 80 - 90°C and react for 2 - 3 hours, and detect the NCO value; when the NCO value reaches the designed value of 98 - 105%, weigh the silane coupling agent according to the proportion and add it to the reaction vessel, keep the temperature at 0.5 - 60°C, and discharge the material to obtain the polyurea component A material;

[0035] S2. Prepare the component B material: Weigh the polyaspartic acid ester resin and antioxidant according to the proportion, add them to the vacuum stirring reaction vessel and start stirring, heat the liquid material to 105 - 115°C; add the pigment filler to the vacuum stirring reaction vessel and stir for 0.5 hour; maintain at 105 - 115°C, evacuate to -0.1 to -0.09 Mpa to remove the moisture in the raw materials until the moisture content of the raw materials drops below five ten-thousandths; add the defoaming agent and leveling agent according to the proportion and stir for 0.5 hour; cool down to 50 - 60°C and discharge the material to obtain the component B material;

[0036] S3. Add the polyurea component A to the metal oxide and micron hollow glass microspheres and mix evenly to obtain a mixed dry powder; as Figure 3 shown, specifically including the following:

[0037] S31. Dry the metal oxide powder and micron hollow glass microspheres;

[0038] Specifically, put the metal oxide powder and micron hollow glass microspheres into the oven for drying. The specific drying time can be determined according to requirements. For example, it can be dried for 12 hours. This step is mainly to remove the moisture in the metal oxide powder and micron hollow glass microspheres.

[0039] S32. Mix the dried metal oxide powder and micron-sized hollow glass microspheres;

[0040] Specifically, mix the dried micron-sized hollow glass microspheres and the metal oxide powder. The mass ratio of the micron-sized hollow glass microspheres to the metal oxide powder is between 0.25 and 1. Use a magnetic stirrer to stir the micron-sized hollow glass microspheres and the metal oxide powder for 5 - 10 minutes to make the two dry powders fully and evenly mixed.

[0041] S33. Add the polyurea component A to the dry powder mixture obtained in step S32 and stir to obtain a mixed dry powder.

[0042] Specifically, during the stirring process, add 3% of the polyaspartic acid ester polyurea component A to the dry powder in 3 - 5 portions within 3 - 5 minutes. Set the mass ratio of the polyurea component A to the mixed dry powder between 0.2 and 1. After adding, continue to stir for about 30 minutes until the powder is evenly dispersed without obvious agglomeration.

[0043] S4. Add the component B material to the mixed dry powder obtained in step S3, and after mixing evenly, obtain a composite spraying material.

[0044] The micron-sized hollow glass microspheres are selected as a mixture of one or more with a particle size of 2μm - 50μm.

[0045] The metal oxide is one or more of powdery Al2O3, TiO2, MgO, CaCO3, ZnO, ZrO2.

[0046] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A daytime passive radiative cooling polyurea composite spraying material with a structure repair function, characterized in that, The composite spraying material includes polyurea component A, component B, multi-graded hollow glass microspheres and metal oxide powder. Among them, component A includes raw materials in the following weight parts: 31-55 parts of isocyanate, 45-69 parts of polyol, and 2-10 parts of silane coupling agent; component B includes raw materials in the following weight parts: 40-80 parts of polyaspartic ester resin, 2-5 parts of defoamer, 1-6 parts of leveling agent, and 1-5 parts of antioxidant.

2. The daytime passive radiative cooling polyurea composite spraying material with structural repair function according to claim 1, wherein: The solar reflectance of the composite spraying material is not less than 95%; the long-wave infrared emissivity is not less than 93%; the flexural strength is not less than 25 MPa, and the compressive strength is not less than 60 Mpa; the porosity is 50%-80%.

3. A preparation method of a daytime passive radiative cooling polyurea composite spraying material with a structural repair function according to any one of claims 1-2, characterized in that: It includes the following steps: S1. Prepare polyurea component A material: Weigh polyol in proportion, add the polyol into a reaction vessel and start stirring; then heat to 105-115 °C; evacuate and dehydrate to remove the moisture in the raw materials; cool the liquid material temperature to 50-60 °C; weigh isocyanate in proportion, add the isocyanate into the reaction vessel and stir for 0.5-1 hour, slowly heat up to 80-90 °C and react for 2-3 hours, and detect the NCO value; when the NCO value reaches the designed value of 98-105%; weigh silane coupling agent in proportion and add it into the reaction vessel, keep the temperature at 0.5-60 °C, and discharge the material to obtain polyurea component A material; S2. Prepare component B material: Weigh polyaspartic ester resin and antioxidant in proportion, add them into a vacuum stirring reaction vessel and start stirring, heat the liquid material to 105-115 °C; add pigments and fillers into the vacuum stirring reaction vessel and stir for 0.5 hour; maintain at 105-115 °C, evacuate and dehydrate to remove the moisture in the raw materials; add defoamer and leveling agent in proportion and stir for 0.5 hour; cool down to 50-60 °C and discharge the material to obtain component B material; S3. Add polyurea component A into metal oxide and micron hollow glass microspheres and mix evenly to obtain a mixed dry powder; S4. Add component B material into the mixed dry powder in step S3, and obtain the composite spraying material after mixing evenly.

4. The preparation method of the daytime passive radiative cooling polyurea composite spraying material with a structural repair function according to claim 3, wherein: In step S1 and step S2, the dehydration after evacuation is specifically: evacuate to -0.1 to -0.09 Mpa to dehydrate and remove the moisture in the raw materials until the moisture content of the raw materials drops below five ten-thousandths.

5. The preparation method of the daytime passive radiative cooling polyurea composite spraying material with structural repair function according to claim 3, characterized in that: In step S3, it specifically includes the following: S31. Dry the metal oxide powder and micron hollow glass microspheres; S32. Mix the dried metal oxide powder and micron hollow glass microspheres; S33. Add polyurea component A into the dry powder mixed in step S32 and stir to obtain a mixed dry powder.

6. The preparation method of the daytime passive radiative cooling polyurea composite spraying material with structural repair function according to claim 5, characterized in that: In step S32, the mass ratio of the micron hollow glass microspheres to the metal oxide is 0.25-1; in step S33, the mass ratio of polyurea component A to the mixed dry powder is 0.2-1.

7. The preparation method of the daytime passive radiative cooling polyurea composite spraying material with structural repair function according to claim 3, characterized in that: The micron hollow glass microspheres are selected from one or more mixtures with a particle size of 2 μm-50 μm.

8. The preparation method of the daytime passive radiative cooling polyurea composite spraying material with structural repair function according to claim 3, characterized in that: The metal oxide is one or more of powdery Al2O3, TiO2, MgO, CaCO3, ZnO, ZrO2.

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