Modified hollow glass microspheres, method for preparing the same, coating and application thereof, and cigarette paper

Abstract

The application relates to modified hollow glass microspheres, a preparation method thereof, a coating and application thereof, and cigarette paper. The modified hollow glass microspheres comprise hollow glass microspheres, a polymer resin film layer and a borate layer; the polymer resin film layer is coated on the surface of the hollow microspheres, and the borate layer is coated on part of the surface of the polymer resin film layer; the material of the polymer resin film layer comprises cross-linked polyvinyl ester. Coating polyvinyl ester on the surface of the hollow glass microspheres can improve the temperature resistance of the hollow glass microspheres, meanwhile, the borate and the polyvinyl ester are physically cross-linked through hydrogen bonds, so that the borate is stably coated on part of the outer surface of the polyvinyl ester, the borate and the polyvinyl ester are mutually synergistic, and the temperature resistance of the hollow glass microspheres is further improved; meanwhile, the modified hollow microsphere structure has good stability.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a modified hollow glass microsphere and its preparation method, coatings and their applications, and cigarette paper. Background Technology

[0002] Coatings can be classified into inorganic and organic types based on their chemical composition. Inorganic coatings mainly consist of inorganic substances and metal oxides, while organic coatings are further subdivided into natural and synthetic series. With technological advancements, coatings require diverse functions, particularly those with properties such as temperature resistance, waterproofing, corrosion resistance, radiation resistance, and flame retardancy, which have garnered significant attention from researchers. This is especially true in paper products, where coatings with waterproof, temperature-resistant, and heat-resistant properties are essential.

[0003] Hollow glass microspheres are a new type of lightweight spherical powder material that is widely used in heat-resistant and heat-insulating coatings. However, the temperature resistance of hollow glass microspheres is relatively poor, which limits their application range. Summary of the Invention

[0004] Therefore, it is necessary to provide modified hollow glass microspheres with good temperature resistance, their preparation methods, coatings and their applications, and cigarette paper.

[0005] The first aspect of this application provides a modified hollow glass microsphere, comprising a hollow glass microsphere, a polymer resin film layer, and a borate layer; the polymer resin film layer covers the surface of the hollow microsphere, and the borate layer covers a portion of the surface of the polymer resin film layer; the material of the polymer resin film layer includes polyvinyl alcohol ester.

[0006] The modified hollow glass microspheres described above include hollow glass microspheres, a polymer resin film layer, and a borate layer. The polymer resin film layer coats the surface of the hollow glass microspheres, and the borate layer coats a portion of the surface of the polymer resin film layer. Polyvinyl alcohol (PVA) has a high melting temperature and contains a large number of hydroxyl groups. After esterification, these hydroxyl groups form a relatively stable cross-linked PVA ester. Coating the surface of the hollow glass microspheres with the PVA ester improves their temperature resistance. Simultaneously, borate forms hydrogen bonds with the hydroxyl groups on the PVA ester, resulting in physical cross-linking between the borate and PVA ester. This allows the borate to stably coat a portion of the outer surface of the PVA ester. The borate and the PVA ester resin film work synergistically to further improve the temperature resistance of the hollow glass microspheres. Furthermore, the hydrogen bonds formed between the PVA ester and borate contribute to the structural stability of the modified hollow microspheres, extending their service life. Adding these modified hollow microspheres to heat-resistant coatings can further improve the coating's temperature resistance and broaden its application areas.

[0007] In some embodiments, the mass ratio of the hollow glass microspheres, the polymer resin film layer, and the borate layer is 1:(3~10):(0.5~1).

[0008] In some embodiments, the modified hollow microspheres further include a silane coupling agent layer grafted onto the surface of the polymer resin film.

[0009] In some embodiments, the mass ratio of the hollow glass microspheres to the silane coupling agent layer is (5~20):1.

[0010] In some embodiments, the modified hollow microspheres satisfy at least one of the following conditions:

[0011] (1) The borate is selected from at least one of sodium borate, potassium borate, calcium borate and iron borate;

[0012] (2) The silane coupling agent is selected from at least one of KH550, KH560 and KH570.

[0013] In some embodiments, the raw materials for preparing the polymer resin film include polyvinyl alcohol and a crosslinking agent.

[0014] A second aspect of this application provides a method for preparing the above-mentioned modified hollow glass microspheres, comprising the following preparation steps:

[0015] A polymer resin film is formed on the surface of the hollow glass microspheres, and then a borate layer is coated on a portion of the surface of the polymer resin film.

[0016] In some embodiments, the method for forming the polymer resin film layer on the surface of the hollow glass microspheres includes the following steps:

[0017] A crosslinking agent is dissolved in a first solvent, and a polymer resin is added to carry out a crosslinking reaction to obtain a polymer resin film solution; the polymer resin includes polyvinyl alcohol.

[0018] Under stirring conditions, the hollow glass microspheres are added to the polymer resin membrane solution to obtain a suspension, which is then filtered, washed, and dried sequentially to obtain hollow glass microspheres with the polymer resin membrane layer on their surface.

[0019] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0020] (1) The crosslinking agent is selected from at least one of citric acid, citrate, malic acid and carbonate;

[0021] (2) The first solvent is at least one of water and ethanol;

[0022] (4) The temperature of the crosslinking reaction is 55℃~90℃, and the time is 0.5h~2h;

[0023] (5) The hollow glass microspheres are added to the polymer resin film solution at 45℃~60℃.

[0024] In some embodiments, the step of coating a portion of the surface of the polymer resin film with a borate layer includes:

[0025] The borate is dissolved in a second solvent to obtain a borate solution;

[0026] Hollow glass microspheres coated with the polymer resin film layer are mixed with the borate solution and stirred at 45℃~60℃ for 3h~12h to form the borate layer on a portion of the surface of the polymer resin film layer of the hollow glass microspheres.

[0027] A third aspect of this application provides a heat-resistant coating, the components of which include a film-forming agent, a surfactant, and the aforementioned modified hollow glass microspheres.

[0028] In some embodiments, the heat-resistant coating may further include one or more of a thickener, a hardener, silicon carbide, a toughening agent, a defoamer, and a leveling agent.

[0029] In some embodiments, the heat-resistant coating comprises, by weight, the following components:

[0030] 50 to 90 parts film-forming agent, 3 to 7 parts thickener, 5 to 20 parts of the modified air glass microspheres, 0.3 to 3 parts surfactant, 0.4 to 2 parts hardener, 0.2 to 1 part silicon carbide, 0.2 to 1 part toughening agent, 0.5 to 1 part defoamer and 0.5 to 2 parts leveling agent.

[0031] In some embodiments, the film-forming agent comprises a hydrated aluminum phosphate complex;

[0032] The preparation method of the hydrated aluminum phosphate complex includes the following steps:

[0033] Aluminum hydroxide is added to an aqueous solution of phosphoric acid to carry out a first reaction, yielding hydrated aluminum phosphate; a complexing agent is added to the hydrated aluminum phosphate to carry out a second reaction, yielding a hydrated aluminum phosphate complex.

[0034] In some embodiments, the method for preparing the hydrated aluminum phosphate complex satisfies at least one of the following conditions:

[0035] (1) The molar mass ratio of Al in the aluminum hydroxide to P in the phosphoric acid is 1:(1.8~2.4).

[0036] (2) The complexing agent is oxalic acid, gluconic acid or succinic acid;

[0037] (3) The amount of the complexing agent added is 2% to 4% of the mass of the hydrated aluminum phosphate;

[0038] (4) The reaction temperature of the first reaction is 120℃~140℃;

[0039] (5) The reaction temperature of the second reaction is 60℃~70℃ and the reaction time is 0.5h-1h.

[0040] A fourth aspect of this application provides a heat-resistant coating, which is made using the aforementioned heat-resistant paint.

[0041] The fifth aspect of this application provides a cigarette paper, the cigarette paper comprising a paper substrate and the aforementioned heat-resistant coating disposed on at least one surface of the paper substrate, or the heat-resistant coating comprises a film-forming agent, a surfactant, and the aforementioned modified hollow glass microspheres.

[0042] The sixth aspect of this application provides a cigarette comprising the aforementioned cigarette paper. Detailed Implementation

[0043] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the weights mentioned in the embodiments of this invention can be well-known units of mass in the chemical industry, such as μg, mg, g, and kg.

[0047] Hollow glass microspheres are a new type of lightweight spherical powder material that is widely used in heat-resistant and heat-insulating coatings. However, the heat resistance of hollow glass microspheres is relatively poor, which limits their application range.

[0048] One embodiment of this application provides a modified hollow glass microsphere, comprising a hollow glass microsphere, a polymer resin film layer, and a borate layer; the polymer resin film layer coats the surface of the hollow microsphere, and the borate layer coats a portion of the surface of the polymer resin film layer; the material of the polymer resin film layer includes polyvinyl alcohol ester.

[0049] The modified hollow glass microspheres described above include hollow glass microspheres, a polymer resin film layer, and a borate layer. The polymer resin film layer coats the surface of the hollow glass microspheres, and the borate layer coats a portion of the surface of the polymer resin film layer. Polyvinyl alcohol (PVA) has a high melting temperature and contains a large number of hydroxyl groups. After esterification, these hydroxyl groups form a relatively stable cross-linked PVA ester. Coating the surface of the hollow glass microspheres with the PVA ester improves their temperature resistance. Simultaneously, borate forms hydrogen bonds with the hydroxyl groups on the PVA ester, resulting in physical cross-linking between the borate and PVA ester. This allows the borate to stably coat a portion of the outer surface of the PVA ester. The borate and the PVA ester resin film work synergistically to further improve the temperature resistance of the hollow glass microspheres. Furthermore, the hydrogen bonds formed between the PVA ester and borate contribute to the structural stability of the modified hollow microspheres, extending their service life. Adding these modified hollow microspheres to heat-resistant coatings can further improve the coating's temperature resistance and broaden its application areas.

[0050] The polyvinyl alcohol resin film can coat all or part of the outer surface of the hollow microspheres. Preferably, the polyvinyl alcohol resin film coats all the outer surface of the hollow microspheres.

[0051] In some embodiments, the mass ratio of the hollow glass microspheres, polymer resin film layer and borate layer in the modified hollow glass microspheres is 1:(3~10):(0.5~1).

[0052] In some embodiments, the raw materials for preparing the polymer resin film include polyvinyl alcohol and a crosslinking agent.

[0053] In some embodiments, the mass ratio of polyvinyl alcohol to crosslinking agent is (3~10):1.

[0054] In some embodiments, the crosslinking agent is selected from at least one of citric acid, citrate, succinic acid, malic acid, and carbonate.

[0055] In some embodiments, the citrate may be at least one of sodium citrate, potassium citrate, aluminum citrate, and ferric citrate.

[0056] In some embodiments, the borate is selected from at least one of sodium borate, potassium borate, calcium borate, and iron borate.

[0057] In some embodiments, the raw materials for preparing modified hollow glass microspheres include hollow glass microspheres, crosslinking agent, polyvinyl alcohol and borate, and the mass ratio of hollow glass microspheres, crosslinking agent, polyvinyl alcohol and borate is 1:1:(3~10):(0.5~1).

[0058] In some embodiments, the modified hollow microspheres further include a silane coupling agent layer grafted onto the surface of the polymer resin film layer. Further grafting the silane coupling agent onto the surface of the polymer resin film layer can improve the compatibility of the modified hollow microspheres with the heat-resistant coating components, thereby further enhancing the storage stability of the heat-resistant coating.

[0059] In some embodiments, the mass ratio of the hollow glass microspheres to the silane coupling agent layer in the modified hollow glass microspheres is (5~20):1. As an example, the mass ratio of the hollow glass microspheres to the silane coupling agent layer in the modified hollow glass microspheres can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1. Further, the mass ratio of the hollow glass microspheres to the silane coupling agent layer in the modified hollow glass microspheres can be any other ratio within the range of (5~20):1.

[0060] In some embodiments, the raw materials for preparing modified hollow glass microspheres further include a silane coupling agent, wherein the mass ratio of hollow glass microspheres to silane coupling agent is (5~20):1. As an example, the mass ratio of hollow glass microspheres to silane coupling agent in the raw materials for preparing modified hollow glass microspheres can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1. Further, the mass ratio of hollow glass microspheres to the silane coupling agent layer in the raw materials for preparing modified hollow glass microspheres can be any other ratio within the range of (5~20):1.

[0061] In some embodiments, the silane coupling agent includes, but is not limited to, at least one selected from KH550, KH560, and KH570. Conventional silane coupling agents with other components may also be selected.

[0062] One embodiment of this application provides a method for preparing the above-mentioned modified hollow glass microspheres, comprising the following preparation steps S10~S20:

[0063] S10. A polymer resin film is formed on the surface of hollow glass microspheres.

[0064] S20, and then a borate layer is coated on a portion of the surface of the polymer resin film.

[0065] In some embodiments, the method of forming a polymer resin film layer on the surface of hollow glass microspheres in step S10 above includes the following steps:

[0066] S101. Dissolve the crosslinking agent in the first solvent, add the polymer resin, and carry out the crosslinking reaction to obtain a polymer resin film solution; the polymer resin includes polyvinyl alcohol.

[0067] S102. Under stirring conditions, hollow glass microspheres are added to a polymer resin membrane solution to obtain a suspension. Then, the suspension is subjected to filtration, washing, and drying processes in sequence to obtain hollow glass microspheres with a polymer resin membrane coating on the surface.

[0068] In some embodiments, the crosslinking agent is selected from at least one of citric acid, citrate, malic acid, and carbonate. In step S101, the polymer resin polyvinyl alcohol is added to the solution containing the crosslinking agent. The polymer resin dissolves during the addition process, and the hydroxyl groups in the dissolved polyvinyl alcohol undergo esterification and crosslinking reactions with the carboxyl groups in the crosslinking agent to obtain a polyvinyl alcohol ester resin film solution.

[0069] In some embodiments, the first solvent is water or ethanol.

[0070] In some embodiments, in step S101, the mass ratio of the added crosslinking agent to the mass of the first solvent is 1:(10~60). As an example, the mass ratio of the added crosslinking agent to the first solvent can be 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, or 1:60. Controlling the mass ratio of the added crosslinking agent to the first solvent ensures that both the crosslinking agent and the polymer resin are fully dissolved.

[0071] In some embodiments, the crosslinking reaction temperature is 55°C to 90°C. Controlling the crosslinking reaction temperature allows polyvinyl alcohol to dissolve more fully and enables the polyvinyl alcohol and crosslinking agent to undergo a more complete esterification and crosslinking reaction.

[0072] In some embodiments, the time is 0.5h to 2h.

[0073] In some embodiments, in step S102, hollow glass microspheres are added to the polymer resin film solution at a temperature of 45°C to 60°C.

[0074] As an improvement, in step S102 above, the hollow glass microspheres can be added to the polymer resin membrane solution at temperatures of 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, or 60℃. Furthermore, the hollow glass microspheres can also be added to the polymer resin membrane solution within a range defined by any two of the above-mentioned point values. Controlling the mixing temperature of the hollow glass microspheres and the polymer resin membrane solution can control the viscosity of the polymer resin membrane system, reduce the crosslinking rate of the polymer resin membrane, and ensure that the polymer resin membrane fully coats the hollow glass microspheres, thereby improving the temperature resistance of the hollow glass microspheres.

[0075] In some embodiments, step S102 further includes the following steps: after adding hollow glass microspheres to a polymer resin membrane solution to obtain a suspension, performing a first ultrasonic treatment, then cooling to room temperature, and then filtering.

[0076] In some embodiments, the ultrasonic frequency of the first ultrasonic treatment is 5kHz to 40kHz, and the ultrasonic time is 0.5h to 1h.

[0077] In some embodiments, step S20, the step of coating a portion of the surface of the polymer resin film with a borate layer, includes:

[0078] S201. Dissolve the borate in a second solvent to obtain a borate solution;

[0079] S202. Hollow glass microspheres coated with polymer resin film are mixed with borate solution and stirred at 45℃~60℃ for 3h~12h to form a borate layer on part of the surface of polymer resin film.

[0080] In some embodiments, the second solvent is water or ethanol.

[0081] In some embodiments, the mass fraction of borate in the borate solution is 1% to 10%.

[0082] In some embodiments, step S20 further includes mixing the hollow glass microspheres coated with a polymer resin film with a borate solution, first ultrasonically dispersing them at 5 kHz to 40 kHz for 5 min to 15 min, and then stirring them at 45 °C to 60 °C for 3 h to 12 h.

[0083] In some embodiments, step S20 further includes the following steps: after stirring is completed, sequentially performing filtration, washing, and drying processes.

[0084] In some embodiments, the drying process is freeze drying at -50°C to -10°C, or vacuum drying at 40°C to 60°C.

[0085] In some embodiments, washing may be performed using water.

[0086] In some embodiments, the preparation method of the modified hollow glass microspheres further includes the following step S30:

[0087] S30, Grafting silane coupling agent onto the surface of the polymer resin film.

[0088] In some embodiments, the step of grafting a silane coupling agent onto the surface of a polymer resin film includes:

[0089] S301. Dissolve the silane coupling agent in a third solvent to obtain a silane coupling agent modified solution;

[0090] S302. Add the modified hollow glass microspheres obtained in step S20 to the silane coupling agent modification solution, and perform ultrasonic treatment, stirring treatment, filtration and drying treatment in sequence to obtain modified hollow glass microspheres with silane coupling agent grafted on the surface of the polymer resin film layer.

[0091] In some embodiments, the mass fraction of the silane coupling agent in the silane coupling agent modified solution is 5% to 20%.

[0092] In some embodiments, the conditions for ultrasonic treatment include: ultrasonic power of 5kHz to 40kHz and ultrasonic time of 5min to 15min.

[0093] In some embodiments, the stirring process is carried out at a temperature of 30°C to 45°C.

[0094] In some embodiments, the stirring time is 30 min to 90 min.

[0095] In some embodiments, the drying process is freeze drying at -50°C to -10°C, or vacuum drying at 40°C to 60°C.

[0096] One embodiment of this application provides a heat-resistant coating, the components of which include a film-forming agent, a surfactant, and modified hollow glass microspheres as described above.

[0097] In some embodiments, the heat-resistant coating may further include one or more of a thickener, a hardener, silicon carbide, a toughening agent, a defoamer, and a leveling agent.

[0098] In some embodiments, the coating comprises, by weight, the following components:

[0099] 50-90 parts film-forming agent, 3-7 parts thickener, 5-20 parts modified air glass microspheres, 0.3-3 parts surfactant, 0.4-2 parts hardener, 0.2-1 part silicon carbide, 0.2-1 part toughening agent, 0.5-1 part defoamer and 0.5-2 parts leveling agent.

[0100] As an example, the film-forming agent component in the coating can be 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, or 90 parts by weight. Further, the weight percentage of the film-forming agent component in the coating can be a range defined by any two of the above points as endpoints. Preferably, the film-forming agent component in the coating is 70 to 90 parts by weight.

[0101] As an example, the modified airy glass microspheres in the coating can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by weight. Furthermore, the weight percentage of the modified airy glass microspheres in the coating can be a range of values ​​defined by any two of the above points as endpoints.

[0102] In some embodiments, the film-forming agent includes a hydrated aluminum phosphate complex. The hydrated aluminum phosphate complex exhibits strong stability and does not precipitate even after two months of storage at room temperature. The use of a hydrated aluminum phosphate complex as a film-forming agent in heat-resistant coatings provides a low film-forming temperature, capable of forming a film at 30°C to 60°C, and exhibiting high film toughness. Adding the hydrated aluminum phosphate complex to the above coating components allows for synergistic effects with other components, further enhancing the stability of the heat-resistant coating, extending its shelf life, and enabling the coating to form a film on paper at room temperature with high film toughness.

[0103] In some embodiments, the preparation method of hydrated aluminum phosphate complex includes the following steps:

[0104] Aluminum hydroxide was added to an aqueous solution of phosphoric acid to carry out a first reaction, yielding hydrated aluminum phosphate; a complexing agent was added to the hydrated aluminum phosphate to carry out a second reaction, yielding a hydrated aluminum phosphate complex.

[0105] In some embodiments, the molar ratio of Al in aluminum hydroxide to P in phosphoric acid is 1:(1.8~2.4). As an example, the molar ratio of Al in aluminum hydroxide to P in phosphoric acid can be 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, or 1:2.4. Further, the molar ratio of Al in aluminum hydroxide to P in phosphoric acid can be any other ratio within the range of 1:(1.8~2.4). Hydrated aluminum phosphate can be obtained by controlling the molar ratio of Al in aluminum hydroxide to P in phosphoric acid. However, hydrated aluminum phosphate easily loses its water of crystallization, forming a precipitate of aluminum tripolyphosphate, which then hardens. Further, after the first reaction is completed, a complexing agent is added. The hydrated aluminum phosphate forms a more stable hydrated aluminum phosphate complex with the complexing agent. Compared to hydrated aluminum phosphate, the hydrated aluminum phosphate complex is less prone to dehydration and hardening, and can maintain a suspension state for a longer period at room temperature.

[0106] In some embodiments, the complexing agent is oxalic acid, gluconic acid, or succinic acid. Preferably, the complexing agent is oxalic acid. Oxalic acid forms a more stable mixture with hydrated aluminum phosphate, resulting in better coating stability.

[0107] In some embodiments, the amount of complexing agent added is 2% to 4% of the mass of hydrated aluminum phosphate. As an example, the amount of complexing agent added can be 2%, 2.2%, 2.5%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.5%, 3.6%, 3.8%, or 4% of the mass of hydrated aluminum phosphate. Further, the amount of complexing agent added can be a range of values ​​defined by any of the above point values ​​as endpoints.

[0108] In some embodiments, the reaction temperature of the first reaction is 120°C to 140°C.

[0109] In some embodiments, the reaction temperature of the second reaction is 60°C to 70°C, and the reaction time is 0.5h to 1h.

[0110] In some embodiments, the surfactant is selected from at least one of 12-hydroxystearic acid and stearic acid.

[0111] In some embodiments, the thickener is selected from at least one of carboxymethyl cellulose, polyacrylamide, stearamide, and polyvinylpyrrolidone.

[0112] In some embodiments, the hardener is selected from at least one of magnesium oxide, aluminum oxide, iron oxide, sodium hydroxide, and talc.

[0113] In some embodiments, the toughening agent may include, but is not limited to, epoxidized soybean oil.

[0114] In some embodiments, the defoamer is selected from at least one of dimethyl silicone oil and polydimethylsiloxane.

[0115] In some embodiments, the leveling agent is selected from at least one of polysiloxane and acrylic acid.

[0116] One embodiment of this application provides a heat-resistant coating, which is made using the aforementioned heat-resistant paint.

[0117] One embodiment of this application provides a cigarette paper, which includes a paper substrate and a heat-resistant coating as described above disposed on at least one surface of the paper substrate, or the heat-resistant coating comprises a film-forming agent, a surfactant, and the modified hollow glass microspheres described above.

[0118] One embodiment of this application provides a cigarette comprising the aforementioned cigarette paper.

[0119] In some embodiments, the cigarettes described above also include tobacco shreds wrapped in cigarette paper.

[0120] To make the objectives, technical solutions, and advantages of this invention clearer and more concise, the invention is described using the following specific embodiments, but the invention is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of the invention and can be used to describe the invention, but should not be construed as limiting the scope of the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0121] To better illustrate the present invention, the following embodiments are provided for further explanation. The specific embodiments are as follows.

[0122] Preparation Examples of Modified Hollow Glass Microspheres

[0123] Example 1

[0124] Example 1 is an example of the preparation of modified hollow glass microspheres, and three sets of modified hollow glass microspheres were prepared, as shown in Examples 1-1, 1-2 and 1-3 respectively.

[0125] Example 1-1

[0126] By weight, the raw materials for preparing modified hollow glass microspheres consist of 1 part hollow glass microspheres, 1 part sodium citrate, 4 parts polyvinyl alcohol, 1 part sodium borate, and 0.1 part silane coupling agent 550.

[0127] (1) Weigh out an appropriate amount of raw materials according to the above formula.

[0128] (2) Dissolve sodium citrate in water, then heat to 90°C, add polyvinyl alcohol and dissolve completely to obtain polyvinyl alcohol film-forming solution, wherein the weight ratio of sodium citrate, polyvinyl alcohol and water is 1:4:50.

[0129] (3) Under the condition of stirring at 50°C, the hollow glass microspheres are added to the polyvinyl alcohol film-forming solution obtained in step (2) and uniformly dispersed into a suspension. The suspension is ultrasonically treated at 30 kHz power for 30 min, then cooled, filtered, washed with deionized water, and freeze-dried at -50°C to obtain hollow glass microspheres coated with polyvinyl alcohol film.

[0130] (4) Dissolve sodium borate in ethanol to obtain a sodium borate solution, wherein the weight ratio of sodium borate to ethanol is 1:10; add the hollow glass microspheres coated with polyvinyl alcohol film obtained in step (3) to the sodium borate solution; ultrasonically treat at 30 kHz for 10 min, then stir at 45 ℃ for 3 h, filter, wash, and vacuum dry at 50 ℃ to obtain the first modified hollow glass microspheres.

[0131] (5) Add silane coupling agent 550 to ethanol to form a silane coupling modification solution, wherein the weight ratio of silane coupling agent to ethanol is 1:30. Add the first modified hollow glass microspheres obtained in step (4) to the silane coupling modification solution; first, sonicate at 30 kHz for 10 minutes, then stir at 45 °C for 90 minutes, filter, and vacuum dry at 50 °C to obtain modified hollow glass microspheres.

[0132] Examples 1-2

[0133] By weight, the raw materials for preparing modified hollow glass microspheres consist of 1 part hollow glass microspheres, 1 part sodium citrate, 8 parts polyvinyl alcohol, 0.5 parts sodium borate, and 0.1 parts silane coupling agent 560.

[0134] (1) Weigh out an appropriate amount of raw materials according to the above formula.

[0135] (2) Dissolve sodium citrate in water, then heat to 90°C, add polyvinyl alcohol and dissolve fully to obtain polyvinyl alcohol film-forming solution, wherein the weight ratio of sodium citrate, polyvinyl alcohol and water is 1:8:50.

[0136] (3) Under the condition of stirring at 50°C, the hollow glass microspheres are added to the polyvinyl alcohol film-forming liquid obtained in step (2) and uniformly dispersed into a suspension; then ultrasonic treatment, cooling, filtration, washing and drying are performed to obtain hollow glass microspheres coated with polyvinyl alcohol film.

[0137] (4) Dissolve sodium borate in ethanol to obtain a sodium borate solution, wherein the weight ratio of sodium borate to ethanol is 1:10; add the hollow glass microspheres coated with polyvinyl alcohol film obtained in step (3) to the sodium borate solution; ultrasonically treat at 30 kHz for 10 min, then stir at 45 ℃ for 3 h, filter, wash, and vacuum dry at 50 ℃ to obtain the first modified hollow glass microspheres.

[0138] (5) Add silane coupling agent 560 to ethanol to form a silane coupling modification solution, wherein the weight ratio of silane coupling agent to ethanol is 1:30. Add the first modified hollow glass microspheres obtained in step (4) to the silane coupling modification solution; first, ultrasonically treat at 30 kHz for 10 minutes, then stir at 45 °C for 90 minutes, filter, and vacuum dry at 50 °C to obtain modified hollow glass microspheres.

[0139] Examples 1-3

[0140] The preparation methods of Examples 1-3 are basically the same as those of Examples 1-1, except that the proportions of hollow glass microspheres, sodium citrate, polyvinyl alcohol and sodium borate are different. By weight, the raw materials for preparing modified hollow glass microspheres in this example contain 1 part hollow glass microspheres, 2 parts sodium citrate, 6 parts polyvinyl alcohol, 1 part sodium borate and 0.1 parts silane coupling agent 550.

[0141] Comparative Example 1

[0142] The preparation method of this comparative example is basically the same as that of Example 1-1, the only difference being that this comparative example only coats the surface of the hollow microspheres with an equal mass of polyvinyl alcohol ester, without coating with a sodium borate layer. Specifically, the preparation method of this comparative example 1 is as follows:

[0143] By weight, the raw materials for preparing modified hollow glass microspheres consist of 1 part hollow glass microspheres, 1 part sodium citrate, 4 parts polyvinyl alcohol, and 0.1 parts silane coupling agent 550.

[0144] (1) Weigh out an appropriate amount of raw materials according to the above formula.

[0145] (2) Dissolve sodium citrate in water, then heat to 90°C, add polyvinyl alcohol and dissolve completely to obtain polyvinyl alcohol film-forming solution, wherein the weight ratio of sodium citrate, polyvinyl alcohol and water is 1:4:50.

[0146] (3) Under the condition of stirring at 50°C, the hollow glass microspheres are added to the polyvinyl alcohol film-forming liquid obtained in step (2) and uniformly dispersed into a suspension; then ultrasonic treatment, cooling, filtration, washing and drying are performed. This process is repeated 5 times to obtain hollow glass microspheres with polyvinyl alcohol film on the surface.

[0147] (4) Add silane coupling agent 550 to ethanol to form a silane coupling modification solution, wherein the weight ratio of silane coupling agent to ethanol is 1:30. Add the hollow glass microspheres with polyvinyl alcohol film coating obtained in step (3) to the silane coupling modification solution; first, sonicate at 30 kHz for 10 minutes, then stir at 45 °C for 90 minutes, filter, and vacuum dry at 50 °C to obtain modified hollow glass microspheres.

[0148] Example 2

[0149] The phosphoric acid solution used in this embodiment is an 85% phosphoric acid solution by mass.

[0150] Example 2 is an example of the preparation of hydrated aluminum phosphate complexes. In Example 2, three groups of hydrated aluminum phosphate complexes were prepared, as shown in Examples 2-1, 2-2, and 2-3 below:

[0151] Example 2-1

[0152] (1) Weigh aluminum hydroxide and phosphoric acid according to the molar mass ratio of Al in aluminum hydroxide and P in phosphoric acid solution of 1:2.1.

[0153] (2) Add aluminum hydroxide to phosphoric acid, heat to 130°C and stir until the solution is clear to obtain hydrated aluminum phosphate; then add oxalic acid to hydrated aluminum phosphate to obtain hydrated aluminum phosphate complex; wherein the mass of oxalic acid added is 4% of the mass of hydrated aluminum phosphate.

[0154] Example 2-2

[0155] The preparation method in this embodiment is basically the same as that in Example 2-1, except that the molar mass ratio of Al in aluminum hydroxide and P in the phosphoric acid aqueous solution is different. In this embodiment, the molar mass ratio of Al in aluminum hydroxide to P in phosphoric acid aqueous solution is 1:2.4; and the added mass of oxalic acid is 4% of the mass of hydrated aluminum phosphate.

[0156] Example 2-3

[0157] The preparation method in this embodiment is basically the same as that in Example 2-1, except that the molar mass ratio of Al in aluminum hydroxide and P in the phosphoric acid aqueous solution is different. In this embodiment, the molar mass ratio of Al in aluminum hydroxide to P in phosphoric acid aqueous solution is 1:1.8; and the added mass of oxalic acid is 4% of the mass of hydrated aluminum phosphate.

[0158] The following are examples of the application of modified hollow glass microspheres in the preparation of coatings.

[0159] Example 3

[0160] Preparation of coatings:

[0161] (1) Prepare the raw materials according to the following formula: 77 parts of the hydrated aluminum phosphate complex prepared in Example 2-1, 3 parts of carboxymethyl cellulose, 15 parts of the second modified hollow glass microspheres prepared in Example 1-1, 1 part of stearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of dimethyl silicone oil and 1 part of polysiloxane.

[0162] (2) The above-mentioned parts by weight of thickener, surfactant, magnesium oxide, silicon carbide, toughening agent, defoamer, leveling agent and hydrated aluminum phosphate complex are mixed and stirred at 80°C for 60 min. Modified hollow glass microspheres are added and stirred for 30 min. Then, ultrasonic treatment is performed for 25 min, and mixing is continued for 4 h. The mixture is then cooled to room temperature to obtain flame-retardant and heat-resistant coating.

[0163] Example 4

[0164] The preparation method of this embodiment is basically the same as that of Example 3. The only difference is that the formulation of the heat-resistant coating is different. The coating component formulation of this embodiment is: 77 parts of hydrated aluminum phosphate complex prepared in Example 2-1, 3 parts of carboxymethyl cellulose, 15 parts of the second modified hollow glass microspheres prepared in Example 1-2, 1 part of stearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of dimethyl silicone oil and 1 part of polysiloxane.

[0165] Example 5

[0166] The preparation method of this embodiment is basically the same as that of Example 3. The only difference is that the formulation of the heat-resistant coating is different. The coating component formulation of this embodiment is: 77 parts of hydrated aluminum phosphate complex prepared in Example 2-1, 3 parts of carboxymethyl cellulose, 15 parts of second modified hollow glass microspheres prepared in Example 1-3, 1 part of stearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of dimethyl silicone oil and 1 part of polysiloxane.

[0167] Example 6

[0168] The preparation method of this embodiment is basically the same as that of Example 3. The only difference is that the formulation of the heat-resistant coating is different. The coating component formulation of this embodiment is: 77 parts of hydrated aluminum phosphate complex prepared in Example 2-2, 3 parts of carboxymethyl cellulose, 15 parts of the second modified hollow glass microspheres prepared in Example 1-1, 1 part of stearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of dimethyl silicone oil and 1 part of polysiloxane.

[0169] Example 7

[0170] The preparation method of this embodiment is basically the same as that of Example 3. The only difference is that the formulation of the heat-resistant coating is different. The coating formulation of this embodiment is: 77 parts of hydrated aluminum phosphate complex prepared in Examples 2-3, 3 parts of carboxymethyl cellulose, 15 parts of the second modified hollow glass microspheres prepared in Examples 1-1, 1 part of stearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of dimethyl silicone oil and 1 part of polysiloxane.

[0171] Example 8

[0172] The preparation method of this embodiment is basically the same as that of Example 3, except that the formulation of the heat-resistant coating is different. The coating formulation of this embodiment is as follows: 82 parts of hydrated aluminum phosphate complex prepared in Example 2-1, 3 parts of polyacrylamide, 10 parts of modified hollow glass microspheres prepared in Example 1-1, 1 part of 12-hydroxystearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of polydimethylsiloxane and 1 part of acrylic acid.

[0173] Example 9

[0174] The preparation method of this embodiment is basically the same as that of Example 3, except that the formulation of the heat-resistant coating is different. The coating formulation of this embodiment is as follows: 87 parts of hydrated aluminum phosphate complex prepared in Example 2-1, 3 parts of polyacrylamide, 5 parts of modified hollow glass microspheres prepared in Example 1-1, 1 part of 12-hydroxystearic acid, 1 part of magnesium oxide, 0.5 parts of silicon carbide, 1 part of epoxidized soybean oil, 0.5 parts of polydimethylsiloxane and 1 part of acrylic acid.

[0175] Example 10

[0176] The preparation method of this embodiment is basically the same as that of Example 3. The only difference is that the composition of the film-forming agent is different when preparing the heat-resistant coating. In this embodiment, the film-forming agent is an equal mass of polyaluminum phosphate (product model: macklin) instead of the hydrated aluminum phosphate complex in Example 3; other process parameters and ratios are the same as those in Example 3.

[0177] Example 11

[0178] The preparation method of Example 11 is basically the same as that of Example 3, except that the composition of the leveling agent is different when preparing the coating. The composition of the leveling agent in this example is polyether modified organosilicon (FAKANUO, specification SRE306B). Other process conditions are the same as those in Example 7.

[0179] Comparative Example 2

[0180] The preparation method of this comparative example is basically the same as that of Example 3, except that the modified hollow glass microspheres used in preparing the coating are different. This comparative example uses the same mass of the modified hollow glass microspheres prepared in Comparative Example 1 when preparing the coating.

[0181] Performance testing

[0182] Thermal conductivity of hollow glass microspheres: The thermal conductivity of the modified hollow glass microspheres prepared in each embodiment and comparative example was tested according to the method specified in GB / T 10295-2008.

[0183] Temperature resistance of hollow glass microspheres: According to the method specified in GB / T 11026.1-2016, the modified hollow glass microspheres prepared in each example and comparative example were placed at 800℃ for 10 hours, and the microsphere morphology was observed to see whether cracking or aging occurred.

[0184] Room temperature storage time test of hydrated aluminum phosphate complex: The hydrated aluminum phosphate prepared in Example 2 was placed at room temperature, and the presence or absence of precipitation was observed and the number of days from the onset of precipitation was recorded.

[0185] Temperature resistance of the paint film: The coatings prepared in each example and comparative example were coated into a paint film with a thickness of 15 μm according to the method specified in GB1735-2007, and the paint film was placed at 250℃ for 24 hours to test the temperature resistance of the paint film prepared in each example and comparative example.

[0186] Coating shelf life: The shelf life of the coatings prepared in each example and comparative example was tested at 25°C according to the method specified in GB 6753.3-1986.

[0187] Film-forming temperature of coatings: The film-forming temperature of the coatings prepared in each example and comparative example was tested according to the method specified in GB 1728-2020.

[0188] Flexibility of coating film: The flexibility of the coating films prepared in each example and comparative example was tested according to the method specified in GB / T6742-2007.

[0189] Flame retardant properties of coatings: The flame retardant properties of the coatings prepared in each example and comparative example were tested according to the method specified in GB / T 2406.3-2022.

[0190] The performance test data for each embodiment and comparative example are shown in Tables 1, 2 and 3 below:

[0191] Table 1

[0192]

[0193] As shown in Table 1, the modified hollow glass microspheres obtained by the preparation method of this application in Examples 1-1 to 1-3 have low thermal conductivity, ranging from 0.067 W / (m·K) to 0.085 W / (m·K), exhibiting good thermal insulation performance. Furthermore, the modified hollow glass microspheres prepared in Examples 1-1 to 1-3 can maintain their morphological integrity even after being heated to 800℃ for 10 hours, demonstrating good temperature resistance.

[0194] The modified hollow glass microspheres prepared in Comparative Example 1, without sodium borate grafting, exhibited a thermal conductivity of 0.115 W / (m·K), higher than those prepared in Examples 1-1 to 1-3. This indicates that the thermal insulation effect of the modified hollow glass microspheres prepared in Comparative Example 1 is inferior to that of Example 1. Furthermore, after 10 hours at 800°C, some of the microspheres in Comparative Example 1 showed signs of cracking and aging, demonstrating that their temperature resistance is inferior to that of Example 1.

[0195] Table 2

[0196]

[0197] Note: The storage time in Table 2 refers to the number of days after the hydrated aluminum phosphate was stored at room temperature before precipitation began. For example, the storage time of the hydrated aluminum phosphate complex in Example 2-1 was 71 days, which means that the hydrated aluminum phosphate complex in Example 2-1 began to precipitate on the 72nd day of storage.

[0198] Table 3

[0199]

[0200] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0201] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A heat-resistant coating, characterized in that, The heat-resistant coating comprises a film-forming agent, a surfactant, and modified hollow glass microspheres. The modified hollow glass microspheres comprise hollow glass microspheres, a polymer resin film layer, and a borate layer; the polymer resin film layer coats the surface of the hollow glass microspheres, and the borate layer coats a portion of the surface of the polymer resin film layer; the polymer resin film layer is made of cross-linked polyvinyl alcohol ester; the mass ratio of the hollow glass microspheres, the polymer resin film layer, and the borate layer is 1:(3~10):(0.5~1); The film-forming agent includes a hydrated aluminum phosphate complex; The preparation method of the hydrated aluminum phosphate complex includes the following steps: Aluminum hydroxide is added to an aqueous solution of phosphoric acid to carry out a first reaction to obtain aluminum hydrated phosphate; a complexing agent is added to the aluminum hydrated phosphate to carry out a second reaction to obtain the aluminum hydrated phosphate complex; the molar mass ratio of Al in the aluminum hydroxide to P in the phosphoric acid is 1:(1.8~2.4).

2. The heat-resistant coating as described in claim 1, characterized in that, The modified hollow glass microspheres also include a silane coupling agent layer, which is grafted onto the surface of the polymer resin film layer.

3. The heat-resistant coating as described in claim 2, characterized in that, The mass ratio of the hollow glass microspheres to the silane coupling agent layer is (5~20):

1.

4. The heat-resistant coating as described in claim 3, characterized in that, The modified hollow glass microspheres satisfy at least one of the following conditions: (1) The borate is selected from at least one of sodium borate, potassium borate, calcium borate and iron borate; (2) The silane coupling agent is selected from at least one of KH550, KH560 and KH570.

5. The heat-resistant coating according to any one of claims 1 to 4, characterized in that, The raw materials for preparing the polymer resin film include polyvinyl alcohol and a crosslinking agent.

6. The heat-resistant coating according to any one of claims 1 to 4, characterized in that, The heat-resistant coating also includes one or more of the following components: thickener, hardener, silicon carbide, toughening agent, defoamer, and leveling agent.

7. The heat-resistant coating as described in claim 6, characterized in that, The heat-resistant coating comprises the following components by weight: 50 to 90 parts film-forming agent, 3 to 7 parts thickener, 5 to 20 parts the modified hollow glass microspheres, 0.3 to 3 parts surfactant, 0.4 to 2 parts hardener, 0.2 to 1 part silicon carbide, 0.2 to 1 part toughening agent, 0.5 to 1 part defoamer and 0.5 to 2 parts leveling agent.

8. The heat-resistant coating according to any one of claims 1 to 4, characterized in that, The method for preparing the hydrated aluminum phosphate complex satisfies at least one of the following conditions: (1) The complexing agent is oxalic acid, gluconic acid or succinic acid; (2) The amount of the complexing agent added is 2% to 4% of the mass of the hydrated aluminum phosphate; (3) The reaction temperature of the first reaction is 120℃~140℃; (4) The reaction temperature of the second reaction is 60℃~70℃ and the reaction time is 0.5h~1h.

9. The method for preparing the heat-resistant coating according to any one of claims 1 to 8, characterized in that, The preparation method of the modified hollow glass microspheres includes the following preparation steps: A polymer resin film is formed on the surface of the hollow glass microspheres, and then a borate layer is coated on a portion of the surface of the polymer resin film.

10. The method for preparing the heat-resistant coating as described in claim 9, characterized in that, The method for forming the polymer resin film layer on the surface of the hollow glass microspheres includes the following steps: A crosslinking agent is dissolved in a first solvent, and a polymer resin is added to carry out a crosslinking reaction to obtain a polymer resin film solution; the polymer resin includes polyvinyl alcohol. Under stirring conditions, the hollow glass microspheres are added to the polymer resin membrane solution to obtain a suspension, which is then filtered, washed, and dried sequentially to obtain hollow glass microspheres with the polymer resin membrane layer on their surface.

11. The method for preparing the heat-resistant coating as described in claim 10, characterized in that, At least one of the following conditions must be met: (1) The crosslinking agent is selected from at least one of citric acid, citrate, malic acid and carbonate; (2) The first solvent is at least one of water and ethanol; (4) The temperature of the crosslinking reaction is 55℃~90℃, and the time is 0.5h~2h; (5) The hollow glass microspheres are added to the polymer resin film solution at 45℃~60℃.

12. The method for preparing the heat-resistant coating according to any one of claims 9 to 11, characterized in that, The step of coating a portion of the surface of the polymer resin film with a borate layer includes: The borate is dissolved in a second solvent to obtain a borate solution; Hollow glass microspheres coated with the polymer resin film layer are mixed with the borate solution and stirred at 45℃~60℃ for 3h~12h to form the borate layer on a portion of the surface of the polymer resin film layer of the hollow glass microspheres.

13. A heat-resistant coating, characterized in that, The heat-resistant coating is made of the heat-resistant coating as described in any one of claims 1 to 8.

14. A type of cigarette paper, characterized in that, The cigarette paper includes a paper substrate and a heat-resistant coating as described in claim 13 disposed on at least one surface of the paper substrate.

15. A cigarette, characterized in that, The cigarette includes the cigarette paper as described in claim 14.

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