Carbon slurry for infrared absorption and preparation method thereof

Abstract

The invention relates to carbonaceous slurry for infrared absorption. The carbonaceous slurry comprises the following components in parts by weight: 500 parts of graphite carbon powder, 600-1000 parts of an organic carrier, 50-200 parts of a dispersing agent and 30-80 parts of an adhesive, the organic carrier specifically comprises the following components in parts by weight: 50-70 parts of glycerol, 10-30 parts of nitrocellulose and 5-15 parts of organic silicon oxide; the dispersing agent is one of sodium phosphate, sodium silicate and sodium carbonate; the binder is one of acrylic resin, polyurethane resin and vinyl chloride. Graphite carbon powder is used as an infrared absorption medium, the used graphite carbon powder medium has the advantages of being easy to disperse, not prone to agglomeration and lower in cost, and meanwhile the preparation process is safe and environmentally friendly; according to the invention, glycerol is selected as an organic carrier, so that the problems of easy volatilization, strong smell and uncontrollable viscosity caused by terpilenol used in the traditional process in the slurry grinding process are avoided; according to the invention, three different agate balls are introduced into the ball milling process, so that carbon powder particles can be fully ground.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic functional slurries, and in particular to a carbonaceous slurry for infrared absorption and a preparation method thereof. Background Art

[0002] Functional slurries are a special type of materials. They usually contain metal or metal oxide particles, which are dispersed in an organic carrier to form a paste or liquid substance. Functional slurries have a wide range of applications in multiple fields such as electronics, energy, and medicine. Their main function is to be coated on a substrate through a specific process and form functional thin films or thick films with functions such as conductivity, insulation, resistance, capacitance, or inductance after sintering.

[0003] Infrared absorption slurries are a special type of functional slurries. They can absorb infrared radiation in specific bands and are widely used in fields such as military camouflage, thermal control coatings, solar energy utilization, medical imaging, and treatment. There are many technical difficulties to be solved in the development of infrared absorption slurries, including the selection and particle size control of infrared absorption materials, the dispersibility of absorption materials in the medium, the cost of absorption materials, safety, and preparation processes. In the existing patents on the preparation technology of infrared absorption slurries, the infrared absorbers used include material systems mainly based on carbon black (such as Chinese patents CN 115678335A, CN105368160 A, CN105907241, CN106280904B, etc.) and material systems mainly based on metal oxides (such as Chinese patents CN112411172B, CN 110079202 A, etc.). As an infrared absorber, carbon black has the advantage of high infrared absorption, but it also has problems such as easy agglomeration, difficult dispersion, easy moisture absorption, and the preparation process affecting the environment and human health. Although the metal oxide-based infrared absorbers do not have problems such as difficult dispersion and unsafe preparation, their infrared absorption rate is lower than that of the carbon black-based ones. In addition, most of the infrared absorption slurry systems described in the existing patent technologies are prepared into coatings by spraying (such as Chinese patents CN 110079202A, CN 115678335 A, CN 113528006A, etc.). The sprayed slurries have the characteristic of low viscosity, and the prepared coatings have the disadvantage of non-uniformity, which is not conducive to the large-scale preparation of coatings.

[0004] Therefore, it is necessary to develop a slurry with high infrared absorption rate, easy dispersion of the absorption medium, low cost, safe production, and capable of uniformly preparing coatings. Summary of the Invention

[0005] The purpose of the present invention is to provide a carbonaceous slurry for infrared absorption and a preparation method thereof to solve the problems raised in the above background art.

[0006] To solve the above technical problems, the present invention is achieved by the following technical measures: A carbonaceous slurry for infrared absorption, characterized in that it comprises the following components in parts by weight: 500 parts of graphite carbon powder, 600 - 1000 parts of organic carrier, 50 - 200 parts of dispersant, and 30 - 80 parts of binder; The specific composition of the organic carrier in parts by weight is: 50 - 70 parts of glycerol, 10 - 30 parts of nitrocellulose, and 5 - 15 parts of organic silicon oxide; The dispersant is one of sodium phosphate, sodium silicate, and sodium carbonate; The binder is one of acrylic resin, polyurethane resin, and vinyl chloride.

[0007] Compared with the prior art, the advantages of the present invention are as follows: The present invention uses graphite carbon powder as the infrared absorption medium. The used graphite carbon powder medium has the advantages of easy dispersion, not easy to agglomerate, and lower cost. At the same time, its preparation process is also safe and environmentally friendly; The present invention selects glycerol with lower volatility as the organic carrier, avoiding the problems of easy volatilization, strong odor, and uncontrollable viscosity caused by terpineol used in the traditional process during the slurry grinding process; The present invention can fully grind carbon powder particles by introducing three different agate balls in the ball milling process.

[0008] As an improvement of the present invention, the particle size range of the graphite carbon powder is 1 - 10μm. The purpose of choosing this design: The graphite carbon powder is selected with a particle size range of 1 - 10μm. The selected graphite carbon powder has a layered structure and a lower surface energy. The layered structure of graphite enables the layers to interact with each other through van der Waals forces, but this force is relatively weak, which helps the sliding between layers and reduces the tendency of particle aggregation. In addition, the surface energy of graphite is relatively low and its chemical stability is relatively high, which also reduces the possibility of interaction between particles and thus is not easy to form aggregates. In comparison, carbon black has an aggregation phenomenon due to its high specific surface area, surface functional groups, and disordered structural characteristics. Therefore, by choosing graphite carbon powder, the problems of difficult dispersion and easy aggregation of the infrared absorption medium can be effectively solved. The graphite carbon powder can be prepared by methods such as graphite pulverization method or biomass pyrolysis method.

[0009] As an improvement of the present invention, the dispersant is a combination of two of sodium phosphate, sodium silicate, and sodium carbonate. The purpose of choosing this design: Sodium phosphate, sodium silicate, and sodium carbonate are inorganic dispersants. Its dispersion mechanism is mainly the electrostatic effect. Inorganic dispersants ionize in water, thickening the double electric layer, increasing the repulsive force between particles, thereby improving the fluidity of the system. At the same time, its price is relatively low and it can be used alone, or mixed in pairs, or all three raw materials can be mixed together when applied.

[0010] The present invention also provides a preparation method for a carbonaceous slurry for infrared absorption, characterized in that it comprises the following steps:

[0011] (1) Weigh each raw material according to the stated parts by weight and place them in an agate ball milling jar.

[0012] (2) According to the ball-to-material ratio, the range of the ball-to-material ratio is 2:1 - 6:1. Weigh the corresponding amount of agate balls and place them in the ball milling jar. Then, place the ball milling jar on a planetary ball mill, set the ball milling time and rotation speed, and start dry milling.

[0013] (3) After the dry milling is completed, add an organic carrier, which is glycerol, to the ball milling jar. Set the ball milling time and rotation speed and start wet milling.

[0014] (4) After the wet milling is completed, test that the appropriate viscosity range of the obtained slurry is within 700 - 4000 mPas, that is, a qualified infrared absorption carbonaceous slurry is prepared.

[0015] As an improvement of the present invention, the ball milling time is 120 - 480 min and the ball milling rotation speed is 200 - 400 r / min. The purpose of selecting this design: If the ball milling rotation speed is lower than the above range, the impact force of the balls on the powder is insufficient, resulting in a longer grinding time; if the ball milling rotation speed is higher than the above range, the ball milling medium moves closely along the inner wall of the jar and does not throw the ball milling medium, greatly weakening the collision and extrusion effect of the ball milling medium on the ball milling material.

[0016] As an improvement of the present invention, the number of the agate balls is composed according to the ratio of large: medium: small of 1:6:3. The purpose of selecting this design: Agate balls have the advantages of high strength, high toughness, no impurities, no reaction, low wear, etc. They have a smooth surface and a small diameter distribution, and are suitable for crushing. Their large, medium and small volumes are matched with each other, and the grinding effect is good.

[0017] As an improvement of the present invention, the wet milling rotation speed is 200 - 400 r / min and the wet milling time is 30 - 60 min. The purpose of selecting this design: If the ball milling rotation speed is lower than the above range, the impact force of the balls on the powder is insufficient, resulting in a longer grinding time; if the ball milling rotation speed is higher than the above range, the ball milling medium moves closely along the inner wall of the jar and does not throw the ball milling medium, greatly weakening the collision and extrusion effect of the ball milling medium on the ball milling material.

[0018] As an improvement of the present invention, the more appropriate viscosity range of the slurry is 2000 - 3000 mPas. The purpose of selecting this design: The viscosity of the slurry directly affects the flow performance and process effect of the slurry. The slurry with appropriate viscosity can flow more smoothly during the processes of transportation, mixing and forming, etc., thereby improving production efficiency. On the contrary, the slurry with too high viscosity will cause difficult flow and is not conducive to the coating on the product surface; the slurry with too low viscosity may make it difficult for the slurry to maintain its shape, which is also not conducive to the coating on the product surface.

[0019] As an improvement of the present invention, the diameters of the large, medium and small agate balls are 1 mm, 0.5 mm and 0.1 mm respectively. The purpose of choosing this design is that the diameters of the large, medium and small agate balls should match the raw materials to be ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0021] In the drawings:

[0022] Figure 1 It is the change of the infrared absorption rate of the coating prepared when the binder of the toner paste described in the present invention is vinyl chloride with the infrared wavelength.

[0023] Figure 2 It is the change of the infrared absorption rate of the coating prepared when the binder of the toner paste described in the present invention is acrylic resin with the infrared wavelength.

[0024] Figure 3 It is the change of the infrared absorption rate of the coating prepared when the binder of the toner paste described in the present invention is polyurethane resin with the infrared wavelength. DETAILED DESCRIPTION OF THE INVENTION

[0025] The preferred embodiments of the present invention are described below with reference to the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0026] A carbonaceous paste for infrared absorption comprises the following components in parts by weight: 500 parts of graphite carbon powder, 600 - 1000 parts of organic carrier, 50 - 200 parts of dispersant, 30 - 80 parts of binder; the specific composition of the organic carrier in parts by weight is: 50 - 70 parts of glycerol, 10 - 30 parts of nitrocellulose, 5 - 15 parts of organic silicon oxide; the dispersant is one of sodium phosphate, sodium silicate and sodium carbonate; the binder is one of acrylic resin, polyurethane resin and vinyl chloride.

[0027] Furthermore, the graphite carbon powder has a particle size range of 1 - 10 μm. The graphite carbon powder is selected with a particle size range of 1 - 10 μm. The selected graphite carbon powder has a layered structure and a low surface energy. The layered structure of graphite enables interaction between layers through van der Waals forces, but this force is relatively weak, facilitating interlayer sliding and reducing the tendency of particle aggregation. In addition, graphite has a relatively low surface energy and high chemical stability, which also reduces the possibility of interaction between particles, thus making it difficult to form aggregates. In comparison, carbon black shows an aggregation phenomenon due to its high specific surface area, surface functional groups, and disordered structural characteristics. Therefore, by selecting graphite carbon powder, the problems of poor dispersion and easy aggregation of the infrared absorption medium can be effectively solved. The graphite carbon powder can be prepared by methods such as graphite pulverization method or biomass pyrolysis method.

[0028] Furthermore, the dispersant is a combination of two of sodium phosphate, sodium silicate, and sodium carbonate. Sodium phosphate, sodium silicate, and sodium carbonate are inorganic dispersants, and their dispersion mechanism is mainly the electrostatic effect. Inorganic dispersants ionize in water, thickening the double electric layer and increasing the repulsive force between particles, thereby improving the fluidity of the system. At the same time, their prices are relatively low, and they can be used alone, in pairs, or in combination of all three raw materials during application.

[0029] The present invention also provides a method for preparing a carbonaceous slurry for infrared absorption, which is characterized by including the following steps:

[0030] (1) Weigh each raw material according to the specified parts by weight and place them in an agate ball mill jar.

[0031] (2) According to the ball-to-material ratio, the range of the ball-to-material ratio is 2:1 - 6:1. Weigh the corresponding amount of agate balls and place them in the ball mill jar, then install the ball mill jar on a planetary ball mill, set the ball milling time and rotation speed, and start dry milling.

[0032] (3) After the dry milling is completed, add an organic carrier, which is glycerol, to the ball mill jar, set the ball milling time and rotation speed, and start wet milling.

[0033] (4) After the wet milling is completed, test that the appropriate viscosity range of the obtained slurry is within 700 - 4000 mPas, that is, a qualified carbonaceous slurry for infrared absorption is prepared.

[0034] Furthermore, the ball milling time is 120 - 480 min, and the ball milling rotation speed is 200 - 400 r / min. If the ball milling rotation speed is lower than the specified range, the impact force of the balls on the powder is insufficient, resulting in a longer grinding time; if the ball milling rotation speed is higher than the specified range, the ball milling medium moves closely along the inner wall of the jar and does not throw the ball milling medium, greatly weakening the collision and extrusion effect of the ball milling medium on the ball milling material.

[0035] Further, the agate balls are composed in a ratio of large : medium : small of 1:6:3. Agate balls have the advantages of high strength, high toughness, no impurities, no reaction, low wear, etc. They have a smooth surface, a small diameter distribution, and are suitable for crushing. Their large, medium, and small volumes are matched with each other, and the grinding effect is good.

[0036] Further, the wet grinding speed is 200 - 400 r / min, and the wet grinding time is 30 - 60 min. If the ball milling speed is lower than the said range, the impact force of the balls on the powder is insufficient, resulting in a longer grinding time; if the ball milling speed is higher than the said range, the ball milling medium moves closely along the inner wall of the tank and will not drop the ball milling medium, greatly weakening the collision and extrusion effect of the ball milling medium on the ball milling material.

[0037] Further, the more suitable viscosity range of the slurry is 2000 - 3000 mPas. The viscosity of the slurry directly affects the flow performance and process effect of the slurry. A slurry with an appropriate viscosity can flow more smoothly during processes such as transportation, mixing, and forming, thereby improving production efficiency. On the contrary, a slurry with too high a viscosity will cause difficult flow and is not conducive to the coating on the product surface; a slurry with too low a viscosity may make it difficult for the slurry to maintain its shape, which is also not conducive to the coating on the product surface.

[0038] Further, the diameters of the large, medium, and small agate balls are 1 mm, 0.5 mm, and 0.1 mm respectively. The diameters of the large, medium, and small agate balls should match the raw materials to be ground.

[0039] Example 1

[0040] Please refer to Figure 1 , a carbonaceous slurry for infrared absorption provided in this example includes the following raw materials in parts by weight:

[0041] 500 parts of graphite carbon powder, 800 parts of organic carrier, 60 parts of dispersant, and 50 parts of binder. The graphite carbon powder has a particle size range of 1 - 10 μm. Among them, in the organic carrier, glycerol accounts for 480 parts, nitrocellulose accounts for 240 parts, and organic silicon oxide accounts for 80 parts. The dispersant is sodium silicate. The binder is vinyl chloride.

[0042] Weigh each raw material according to the said parts by weight and put them into an agate ball mill tank. According to a ball - to - material ratio of 3:1, weigh agate balls and put them into the ball mill tank. Then install the ball mill tank on a planetary ball mill, set the ball milling time to 3 h and the speed to 300 r / min, and start dry grinding; after the dry grinding is completed, add a certain amount of organic carrier to the ball mill tank, set the ball milling time to 40 min and the speed to 300 r / min, and start wet grinding; after the wet grinding is completed, test the viscosity range of the obtained slurry to be 700 - 4000 mPas, and thus the required carbonaceous slurry for infrared absorption is prepared.

[0043] To verify the printability and infrared absorption performance of the prepared infrared absorption paste, in this embodiment, the prepared paste was printed on a 4×4 mm2 ceramic chip containing 96% Al2O3 using screen printing technology. It was placed in an oven at 80 °C and baked for 30 min, then taken out and cooled to room temperature, thus preparing a thick-film coating. Then, the infrared absorption performance of the prepared coating was tested using an infrared spectrometer, and the results are as Figure 1 shown. The prepared coating has a high infrared absorption rate in the 1.5 μm - 15 μm band, above 90%.

[0044] Example 2

[0045] Please refer to Figure 2 , a carbonaceous paste for infrared absorption provided in this embodiment includes the following raw materials in parts by weight:

[0046] 500 parts of graphite carbon powder, 800 parts of organic carrier, 60 parts of dispersant, and 50 parts of binder. The graphite carbon powder has a particle size range of 1 - 10 μm. Among them, in the organic carrier, glycerol accounts for 480 parts, nitrocellulose accounts for 240 parts, and organosilica accounts for 80 parts. The dispersant is sodium silicate. The binder is acrylic resin.

[0047] Weigh each raw material according to the above parts by weight and put them into an agate ball milling tank. According to a ball-to-material ratio of 3:1, weigh agate balls and put them into the ball milling tank. Then, install the ball milling tank on a planetary ball mill, set the ball milling time to 3 h and the rotation speed to 300 r / min, and start dry milling; after the dry milling is completed, add a certain amount of organic carrier to the ball milling tank, set the ball milling time to 40 min and the rotation speed to 300 r / min, and start wet milling; after the wet milling is completed, test the viscosity range of the obtained paste to be 700 - 4000 mPas, thus preparing the required infrared absorption carbonaceous paste.

[0048] To verify the printability and infrared absorption performance of the prepared infrared absorption paste, in this embodiment, the prepared paste was printed on a 4×4 mm2 ceramic chip containing 96% Al2O3 using screen printing technology. It was placed in an oven at 80 °C and baked for 30 min, then taken out and cooled to room temperature, thus preparing a thick-film coating. Then, the infrared absorption performance of the prepared coating was tested using an infrared spectrometer, and the results are as Figure 2 shown. The prepared coating has a high infrared absorption rate in the 1.5 μm - 15 μm band, above 80%.

[0049] Example 3

[0050] Please refer to Figure 3 , a carbonaceous paste for infrared absorption provided in this embodiment includes the following raw materials in parts by weight:

[0051] 500 parts of graphite carbon powder, 800 parts of organic carrier, 60 parts of dispersant, and 50 parts of binder. The particle size range of the graphite carbon powder is 1 - 10 μm. Among them, in the organic carrier, 480 parts are glycerol, 240 parts are nitrocellulose, and 80 parts are organic silicon oxide. The dispersant is sodium silicate. The binder is polyurethane resin.

[0052] Weigh each raw material according to the above weight parts and put them into an agate ball milling tank. According to the ball - to - material ratio of 3:1, weigh agate balls and put them into the ball milling tank. Then install the ball milling tank on a planetary ball mill, set the ball milling time to 3 h and the rotation speed to 300 r / min, and start dry milling. After the dry milling is completed, add a certain amount of organic carrier to the ball milling tank, set the ball milling time to 40 min and the rotation speed to 300 r / min, and start wet milling. After the wet milling is completed, test the viscosity range of the obtained slurry to be 700 - 4000 mPas, that is, the required infrared - absorbing carbonaceous slurry is prepared.

[0053] To verify the printability and infrared absorption performance of the prepared infrared - absorbing slurry, in this example, the prepared slurry is printed on a 4×4 mm2 ceramic chip containing 96% Al2O3 using screen - printing technology, placed in an oven at 80 °C, baked for 30 min, and then taken out and cooled to room temperature, that is, a thick - film - type coating is prepared. Then, use an infrared spectrometer to test the infrared absorption performance of the prepared coating, and the obtained results are as Figure 2 shown. The prepared coating has a relatively high infrared absorption rate in the 1.5 μm - 15 μm band, above 85%.

[0054] Compared with the prior art, the beneficial effects of the present invention are:

[0055] 1. The present invention uses graphite carbon powder as the infrared - absorbing medium, replacing the carbon black solution in the conventional technology. In comparison, the used graphite carbon powder medium has the advantages of easy dispersion, not easy to agglomerate, and lower cost. At the same time, its preparation process is also safe and environmentally friendly.

[0056] 2. In the design of the slurry composition, the present invention selects glycerol with relatively low volatility as the organic carrier, avoiding the problems of easy volatilization, strong odor, and uncontrollable viscosity caused by terpineol used in the traditional process during the slurry grinding process.

[0057] 3. The present invention can fully grind carbon powder particles by introducing three different agate balls in the ball - milling process. If the ball - milling rotation speed is lower than the range, the impact force of the balls on the powder is insufficient, resulting in a longer grinding time. If the ball - milling rotation speed is higher than the range, the ball - milling medium moves closely along the inner wall of the tank and does not throw the ball - milling medium, greatly weakening the collision and extrusion effect of the ball - milling medium on the ball - milling material.

[0058] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0059] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. 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 in the protection scope of the present invention.

Claims

1. A carbonaceous slurry for infrared absorption, characterized in that: The invention comprises the following components in parts by weight: 500 parts of graphite carbon powder, 600-1000 parts of organic carrier, 50-200 parts of dispersant and 30-80 parts of adhesive; the specific composition of the organic carrier in parts by weight is: 50-70 parts of propylene glycol, 10-30 parts of nitrocellulose and 5-15 parts of organic silicon oxide; the dispersant is one of sodium phosphate, sodium silicate and sodium carbonate; the adhesive is one of acrylic resin, polyurethane resin and vinyl chloride.

2. The carbonaceous slurry for infrared absorption according to claim 1, characterized in that: The graphite carbon powder has a particle size range of 1-10 μm.

3. The carbonaceous slurry for infrared absorption according to claim 1, characterized in that: The dispersant is a combination of two of sodium phosphate, sodium silicate and sodium carbonate.

4. A method for preparing a carbonaceous slurry for infrared absorption as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Weighing each raw material according to the weight portion and placing it in an agate ball mill; (2) According to the ball-to-material ratio, which ranges from 2:1 to 6:1, weigh the corresponding amount of agate balls and put them in a ball mill, then install the ball mill on a planetary ball mill, set the ball milling time and speed, and start dry grinding; (3) After the dry milling is completed, an organic carrier is added to the ball mill, wherein the organic carrier is propylene glycol, the ball milling time and speed are set, and wet milling is started; (4) After wet grinding, the suitable viscosity of the slurry obtained by testing is within the range of 700-4000 mPas, that is, a qualified infrared absorbing carbonaceous slurry is prepared.

5. The carbonaceous slurry for infrared absorption according to claim 4, characterized in that: The ball milling time is 120-480 min, and the ball milling speed is 200-400 r / min.

6. The carbonaceous slurry for infrared absorption according to claim 4, characterized in that: The number of the agate balls is in the ratio of large, medium and small 1:6:

3.

7. The carbonaceous slurry for infrared absorption according to claim 4, characterized in that: The wet grinding speed is 200-400r / min, and the wet grinding time is 30-60min.

8. The carbonaceous slurry for infrared absorption according to claim 4, characterized in that: The more suitable viscosity range of the slurry is 2000-3000 mPas.

9. The carbonaceous slurry for infrared absorption according to claim 4, characterized in that: The diameters of the large, medium and small agate balls are 1 mm, 0.5 mm and 0.1 mm respectively.

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