Preparation method and application of silicon-titanium compound for thermo-sensitive paper

Abstract

The invention belongs to the field of new material technology application, and particularly relates to a preparation method of a silicon-titanium compound for thermo-sensitive paper, which comprises the following steps: S1, preparing a water glass solution and a sulfuric acid solution; s2, adding a water glass solution into a reaction kettle, and then gradually adding a titanyl sulfate solution to form silicon-titanium gel; s3, fully stirring and keeping a certain pH value, adding a water glass solution and a sulfuric acid solution, then adding an amino silane coupling agent, adjusting the pH value, raising the temperature and pressure, aging, and aging under an acidic condition to generate a precipitated silicon-titanium compound; and S4, washing the silicon-titanium compound with pure water, an ammonium salt aqueous solution and pure water in sequence, drying, and crushing with a fluidized bed jet mill. The prepared silicon-titanium compound is large in pore volume, high in whiteness and easy to disperse, has the advantages of being high in whiteness, good in dispersity, excellent in ink absorbency and the like in the field of thermo-sensitive paper, and is easy to industrialize.

Description

Technical Field

[0001] This invention belongs to the field of new material technology application, specifically relating to a method for preparing and applying a silicon-titanium composite for thermal paper. Background Technology

[0002] Thermal paper, as a type of information recording material, is widely used in fields such as tickets, labels, faxes, medical imaging, and cash register receipts due to its advantages such as no need for ribbons or ink ribbons on printing equipment, fast printing speed, low noise, and ease of use. Its color development principle mainly utilizes the chemical reaction between colorless dyes and color developers in the thermal coating under heating conditions to develop color images. However, traditional thermal paper has the following problems during use: poor preservation stability; the printed text is prone to fading or yellowing under light, heat, plasticizers, and humidity, leading to information loss and affecting information preservation; poor chemical resistance; the text is easily blurred when in contact with chemicals such as alcohol, grease, and plasticizers; difficulty in balancing background whiteness and image contrast; fluorescent whitening agents are often added to improve background whiteness, but this affects the initial contrast of the image, and sometimes background whiteness is sacrificed to improve contrast.

[0003] To address these issues, existing technologies often add various fillers to the thermal coating, such as silica, kaolin, calcium carbonate, and titanium dioxide. Titanium dioxide provides excellent opacity and whiteness, but its photocatalytic activity may accelerate dye fading under prolonged light exposure. Silica has good porosity and adsorption properties, which are beneficial for the color development reaction, but its whiteness is limited. Chinese patent CN116716762A discloses an environmentally friendly and durable thermal paper and its preparation method, in which inorganic fillers of silica and titanium dioxide account for 40-60 parts. Simply physically mixing titanium dioxide and silica results in unstable product performance, making it difficult to achieve optimal performance from both. Furthermore, excessive inorganic fillers can damage the print head, easily generate waste, and reduce color development sensitivity.

[0004] Therefore, developing a silicon-titanium composite that combines the advantages of both silicon dioxide and titanium dioxide is of great significance for improving the overall performance of thermal paper. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing and applying a silicon-titanium composite for thermal paper. The silicon-titanium composite prepared by this invention has large pore volume, high whiteness, and low particle size, and has advantages such as high whiteness, good dispersibility, and excellent ink absorption in the field of silicon dioxide application for thermal paper.

[0006] The primary objective of this invention is to provide a method for preparing a silicon-titanium composite for thermal paper.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing and applying a silicon-titanium composite for thermal paper includes the following steps:

[0009] S1. Prepare water glass solution and sulfuric acid solution;

[0010] S2. Add water glass solution to the reaction vessel, then add titanium oxysulfate solution to obtain a mixed solution and form a silicon-titanium gel;

[0011] S3. Stir the silicon-titanium gel thoroughly, while maintaining the pH, add water glass solution and sulfuric acid solution, then add amino-type silane coupling agent, maintain high temperature and high pressure aging to form silicon-titanium precipitate, then adjust the pH to acidic and age to generate silicon-titanium complex.

[0012] S4. The silicon-titanium composite is washed sequentially with pure water, ammonium salt aqueous solution, and pure water, dried, and then pulverized by an air jet mill to obtain the final product.

[0013] Preferably, the modulus of the water glass in step S1 is 3.50~3.80, the concentration of silica in the water glass solution is 5wt%~15wt%, and the concentration of the sulfuric acid solution is 5wt%~10wt%.

[0014] Preferably, after adding the titanium oxysulfate solution in step S2, the concentration of TiO2 in the mixed solution is 5wt%~10wt%, and the sulfuric acid content in the mixed solution is 5wt%~10wt%.

[0015] Preferably, the amount of water glass solution added in step S2 is 5% to 20% of the total amount of water glass, and the amount of titanium oxysulfate added satisfies the mass ratio of titanium to silicon of 1:(1~2).

[0016] Preferably, when adding water glass solution and sulfuric acid solution in step S3, the amount of water glass solution added is the remaining percentage of the reaction content in step S2. For example, 5% to 20% of the total water glass amount is added in step S2, and 80% to 95% of the remaining water glass amount is added in step S3.

[0017] Preferably, the amino-type silane coupling agent added in step S3 is one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-ethyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, or 3-aminopropylmethyldiethoxysilane, and its content is 1% to 2% of the silicon-titanium composite.

[0018] Preferably, in step S3, the silicon-titanium gel is thoroughly stirred, the pH is maintained at 8-11, the aging temperature is 120-150℃, the pressure is 0.5-0.8MPa, and then the pH is adjusted to 2-4.

[0019] Preferably, the washing in step S4 refers to washing the silica gel in the following order: pure water, ammonium salt aqueous solution, and pure water in a washing time ratio of 2:5:3, until the conductivity of the silica gel is below 150 μs / cm; wherein the conductivity of the pure water is below 5 μs / cm, the temperature is 40℃~70℃, the ammonium salt is one of ammonium sulfate, ammonium bisulfate, ammonium carbonate, or ammonium bicarbonate, and the mass concentration of the ammonium salt aqueous solution is 0.10%~0.50wt%.

[0020] Preferably, the air jet milling in step S4 uses an alumina ceramic liner, a zirconia ceramic liner, or a zirconia-toughened alumina ceramic liner for the grinding chamber.

[0021] The raw materials and their quantities in this invention are as follows:

[0022] This invention also claims protection for a silicon-titanium composite for thermal paper prepared by the method described above.

[0023] Furthermore, the whiteness of the silicon-titanium composite for thermal paper is 99.2%~99.8%, and the pore volume is 1.20 cm³. 3 / g~1.50cm 3 / g, bulk density 0.30g / cm³ 3 ~0.40g / cm 3 The silica content is 90%~95%, the titanium content is 4%~8%, and the D50 particle size is 2.0~4.0 micrometers.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The silicon-titanium composite synthesized in this application can ensure the whiteness, hardness and pore volume of the product, and ensure that the ink absorption of the product is greatly improved and the best performance is achieved;

[0026] (2) The initial temperature for preparing silica sol in this application is 30~50℃, and the temperature and pressure are increased to 120~150℃ and 0.5~1.0 MPa during aging. The initial low temperature and low pressure conditions help to form a larger primary silicon-titanium particle structure, ensuring that the primary silicon-titanium particles grow slowly; while the aging temperature is 120~150℃ and the aging pressure is 0.5~1.0 MPa. The high temperature and high pressure during the aging process can accelerate the rapid growth of silicon-titanium particles. The resulting silicon-titanium composite has a large pore volume and strong stability, which can further improve the ink absorption of silicon-titanium in the thermal paper system.

[0027] (3) The aging process of the amino-type silane coupling agent added in this application is carried out under alkaline conditions. The amino-type silane coupling agent can play its maximum role under alkaline conditions. Secondly, the amino group in the silane coupling agent has high reactivity, which can accelerate the cross-linking of the silicon-titanium composite, so that the silicon-titanium composite exhibits better dispersibility characteristics in the thermal paper system.

[0028] (4) The grinding chamber of the fluidized bed air jet mill used in this application must be lined with alumina ceramic, zirconia ceramic, or zirconia-toughened alumina ceramic. It is mainly suitable for grinding high-hardness silicon-titanium composites. The grinding chamber must be lined with the above materials so that the fluidized bed equipment can process these high-hardness materials in a long time, stably and purely, thereby ensuring the quality of silicon-titanium composite products and production efficiency. Detailed Implementation

[0029] The technical solution for synthesizing silica for matte finish in elastic tactile paint according to the present invention will be clearly and completely described below with reference to embodiments and comparative examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0031] Example 1

[0032] At 30°C, a 5wt% water glass solution (representing 10% of the total water glass mass) was added to the reactor. After 30 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The mixed solution contained 5wt% TiO2 and approximately 5wt% sulfuric acid, maintaining a 1:1 ratio of titanium to silicon. Stirring was stopped after the titanium oxysulfate was added. After aging for 30 minutes, the mixture was further dispersed by slurrying for 30 minutes. Then, a 5wt% water glass solution and 5% titanium oxysulfate were simultaneously added to the reactor. A wt% sulfuric acid solution was added, maintaining the pH of the solution at 8. Then, 1% (of the silicon-titanium content) of 3-aminopropyltriethoxysilane was added, maintaining the pH at 8. The temperature was raised to 120°C and the pressure to 0.5 MPa. The reaction was aged for 90 minutes under these pH conditions. The pressure in the reactor was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 70°C. Sulfuric acid was added at this temperature to adjust the pH to 2.0, and the reactor was aged for 20 minutes. After aging, the reactor was drawn into a filter press and washed sequentially with 40°C hot pure water, 0.1% ammonium salt aqueous solution, and 40°C hot pure water at intervals of 2:5:3. The washing time was 6 hours, until the conductivity was below 150 μS / cm. After washing, the reactor was spray-dried and then pulverized to a particle size of 2.0~4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0033] Test methods and standards for the physicochemical properties of products:

[0034] (1) Whiteness test: The whiteness shall be determined according to the method specified in GB / T 23774-2009;

[0035] (2) Pore volume test: Fully automated specific surface area and pore volume analysis using McTristar II 3020;

[0036] (3) Bulk density test: The bulk density test shall be carried out in accordance with the test plan of GB / T 16913-2008;

[0037] (4) Silica content test: The silica content is determined by the mass difference before and after ignition after treating silica with hydrofluoric acid;

[0038] (5) Titanium content test: Inductively coupled plasma optical emission spectrometry (ICP-OES);

[0039] (6) Average particle size test: Malvern 3000 laser particle size analyzer;

[0040] The physicochemical properties of the seven parallel products are shown in Table 1.

[0041] Table 1. Physicochemical properties of the sample from Example 1

[0042] Example 2

[0043] At a temperature of 50℃, a water glass solution with a concentration of 15wt% and a reaction mass ratio of 20% of the total water glass was added to the reactor. After 60 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The concentration of TiO2 in the mixed solution was 10wt%, the sulfuric acid content was about 10wt%, and the titanium-silicon element content of the titanium oxysulfate mixed solution was maintained at 1:2. After the titanium oxysulfate was added, stirring was stopped. After aging for 60 minutes, the mixture was then slurried and dispersed for another 60 minutes. A 15 wt% water glass solution and a 10 wt% sulfuric acid solution were simultaneously added to the reactor, maintaining the pH of the solutions at 11. Then, 2% (of the silicon-titanium content) of 3-aminopropyltrimethoxysilane was added, maintaining the pH at 11. The temperature was raised to 150°C and the pressure to 1.0 MPa. The reaction was aged for 120 minutes under these pH conditions. The reactor pressure was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 90°C. Sulfuric acid was added at this temperature to adjust the pH to 5.0, and the mixture was aged for 60 minutes. After aging, the mixture was drawn into a filter press and washed sequentially with 70°C hot pure water, 0.5% ammonium salt aqueous solution, and 70°C hot pure water at intervals of 2:5:3. The washing time was 3 hours, until the conductivity was below 150 μS / cm. After washing, the mixture was spray-dried and then pulverized to a particle size of 2.0–4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0044] Example 3

[0045] At 40℃, a 10wt% water glass solution (representing 15% of the total water glass mass) was added to the reactor. After 45 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The mixed solution contained 8wt% TiO2 and approximately 8wt% sulfuric acid, maintaining a titanium-silicon ratio of 1:1.5. Stirring was stopped after the addition of titanium oxysulfate was complete. After aging for 45 minutes, the mixture was further dispersed by slurrying for 45 minutes. Simultaneously, a 10wt% water glass solution and 8wt% TiO2 were added to the reactor. A wt% sulfuric acid solution was added, maintaining the pH of the solution at 9.5. Then, 1.5% N-2-(aminoethyl)-3-aminopropyltriethoxysilane (based on the silicon-titanium content) was added, maintaining the pH at 9.5. The temperature was then raised to 135℃ and the pressure to 0.75 MPa. The reaction was aged for 105 minutes under these pH conditions. The pressure in the reactor was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 80℃. Sulfuric acid was added at this temperature to adjust the pH to 3.5, and the mixture was aged for 20 minutes. After aging, the mixture was drawn into a filter press and washed sequentially with 50℃ hot pure water, 0.3% ammonium salt aqueous solution, and 50℃ hot pure water at intervals of 2:5:3. The washing time was 4.5 hours, until the conductivity was below 150 μs / cm. After washing, the mixture was spray-dried and then pulverized to a particle size of 2.0~4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0046] Example 4

[0047] At 35℃, a 7wt% water glass solution (representing 14% of the total water glass mass) was added to the reactor. After 40 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The mixed solution contained 7wt% TiO2 and approximately 7wt% sulfuric acid, maintaining a titanium-silicon ratio of 1:1.25. Stirring was stopped after the titanium oxysulfate was added. After aging for 40 minutes, the mixture was further dispersed by slurrying for 40 minutes. Simultaneously, a 7wt% water glass solution and 6% titanium oxysulfate were added to the reactor. A wt% sulfuric acid solution was added, maintaining the pH of the solution at 9. Then, 1.25% N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (based on the silicon-titanium content) was added, maintaining the pH at 9. The temperature was then raised to 130℃ and the pressure to 0.7 MPa. The reaction was aged for 100 minutes under these pH conditions. The pressure of the reactor was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 75℃. Sulfuric acid was added at this temperature to adjust the pH to 3.0, and the reactor was aged for 30 minutes. After aging, the reactor was drawn into a filter press and washed sequentially with 50℃ hot pure water, 0.2% ammonium salt aqueous solution, and 50℃ hot pure water at intervals of 2:5:3. The washing time was 4 hours, until the conductivity was below 150 μs / cm. After washing, the reactor was spray-dried and then pulverized to a particle size of 2.0~4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0048] Example 5

[0049] At 45℃, a 12.5wt% water glass solution (representing 18% of the total water glass mass) was added to the reactor. After 50 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The mixed solution contained 9wt% TiO2 and approximately 9wt% sulfuric acid, maintaining a titanium-silicon ratio of 1:1.75. Stirring was stopped after the titanium oxysulfate was added. After aging for 50 minutes, the mixture was further dispersed by slurrying for 50 minutes. Simultaneously, a 12.5wt% water glass solution and 7.5% titanium oxysulfate were added to the reactor. A wt% sulfuric acid solution was added, maintaining the pH of the solution at 10. Then, 1% N-ethyl-3-aminopropyltrimethoxysilane (based on the silicon-titanium content) was added, maintaining the pH at 10. The temperature was raised to 140℃ and the pressure to 0.8 MPa. The reaction was aged for 110 minutes under these pH conditions. The pressure of the reactor was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 75℃. Sulfuric acid was added at this temperature to adjust the pH to 4.0, and the mixture was aged for 40 minutes. After aging, the mixture was drawn into a filter press and washed sequentially with 60℃ hot pure water, 0.4% ammonium salt aqueous solution, and 60℃ hot pure water at intervals of 2:5:3. The washing time was 5 hours, until the conductivity was below 150 μs / cm. After washing, the mixture was spray-dried and then pulverized to a particle size of 2.0~4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0050] Example 6

[0051] At 40℃, a 10wt% water glass solution (representing 10% of the total water glass mass) was added to the reactor. After 45 minutes, titanium oxysulfate (TiOSO4) was added to obtain a mixed solution. The mixed solution contained 9wt% TiO2 and approximately 9wt% sulfuric acid, maintaining a titanium-silicon ratio of 1:1.5. Stirring was stopped after the titanium oxysulfate was added. After aging for 45 minutes, the mixture was further dispersed by slurrying for 45 minutes. Simultaneously, a 10wt% water glass solution and 7.5% iodine sulfate were added to the reactor. A wt% sulfuric acid solution was added, maintaining the pH of the solution at 9.5. Then, 1.5% N-phenyl-3-aminopropyltrimethoxysilane (based on the silicon-titanium content) was added, maintaining the pH at 9.5. The temperature was raised to 140℃ and the pressure to 0.9 MPa. The reaction was aged for 100 minutes under these pH conditions. The pressure in the reactor was then reduced to atmospheric pressure, and pure water was added to lower the temperature to 80℃. Sulfuric acid was added at this temperature to adjust the pH to 3.0, and the mixture was aged for 30 minutes. After aging, the mixture was drawn into a filter press and washed sequentially with 50℃ hot pure water, 0.25% ammonium salt aqueous solution, and 50℃ hot pure water at intervals of 2:5:3. The washing time was 4 hours, until the conductivity was below 150 μs / cm. After washing, the mixture was spray-dried and then pulverized to a particle size of 2.0~4.0 micrometers using an alumina ceramic-lined airflow pulverizer, thus obtaining the silicon-titanium composite for thermal paper.

[0052] Comparative Example 1

[0053] The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 does not add titanium oxysulfate, but only adds sulfuric acid solution, while the other operations are the same as in Example 1.

[0054] Comparative Example 2

[0055] The difference between Comparative Example 2 and Example 1 is that the initial reaction temperature of Comparative Example 2 is not 30~50℃, but the initial temperature of the reactor is 10~25℃. Other operations are the same as those in Example 1.

[0056] Comparative Example 3

[0057] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 does not contain amino coupling agents such as 3-aminopropyltriethoxysilane, while the other operations are the same as in Example 1.

[0058] Comparative Example 4

[0059] The difference from Example 1 is that after adding the silane coupling agent in Comparative Example 4, the pH was kept at 8-11, and the temperature was not raised to 120-150°C and the pressure was kept at 0.5-1.0 MPa, but rather controlled at 90-100°C and atmospheric pressure. Other operations were the same as in Example 1.

[0060] Comparative Example 5

[0061] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not use 40°C hot pure water, 0.1% ammonium salt aqueous solution, and 40°C hot pure water in a washing sequence with time intervals of 2:5:3 and a washing time of 6 hours. Instead, it directly uses 40-70°C water for 6 hours. Other operations are the same as in Example 1.

[0062] Comparative Example 6

[0063] The difference from Example 1 is that the fluidized bed air jet mill used for pulverization has a common ceramic lining instead of an alumina ceramic lining, a zirconia ceramic lining, or a zirconia-toughened alumina ceramic lining. Other operations are the same as in Example 1.

[0064] Results Analysis

[0065] The testing methods and standards for the physical and chemical properties of the products are the same as in Example 1. The physical and chemical properties of the products in the other examples and comparative examples are shown in Table 2.

[0066] Table 2 Comparison of physicochemical properties of the examples and comparative samples

[0067] As can be seen from the test data of the sample examples in Tables 1 and 2, the physicochemical properties of the products produced according to the technical solution of the present invention are basically similar, indicating that the production of the technical solution is stable.

[0068] As shown in Table 2, in Comparative Example 1, without introducing titanium and using sulfuric acid instead of titanium oxysulfate to react with water glass, the pore volume of the sample increased, while the whiteness and packing density decreased significantly. This is because the silicon-titanium composite formed by the reaction of titanium oxysulfate and water glass has high whiteness, and the resulting titanium dioxide partially fills the silica pores, compressing the pore volume while increasing the mass per unit volume. Furthermore, the Si-O-Si and Ti-O-Si bonds formed in the reaction result in dense cross-linking of the framework, further compressing the pores, reducing the pore volume, and increasing the packing density.

[0069] Compared to Example 1, Comparative Example 2, where the reactor temperature was not between 30 and 50°C, showed a decrease in sample pore volume and an increase in packing density. The main reason is that the initial temperature was below 30°C, resulting in a low hydrolysis rate of titanium oxysulfate, incomplete water glass condensation, small primary silicon-titanium particles, and a slow, uneven overall reaction. Local residues easily blocked the silica channels, leading to a decrease in overall pore volume and an increase in packing density. The applicant also experimented with reactor temperatures between 50 and 90°C. Higher temperatures accelerated the hydrolysis rate of titanium oxysulfate, leading to excessive water glass hydrolysis and condensation, resulting in larger primary silicon-titanium particles. However, this increased the richness of the silicon-titanium gel framework, resulting in excessive overall density and pore compression, thus causing a decrease in pore volume and an increase in packing density. Therefore, maintaining a temperature between 30 and 50°C ensures a moderate reaction rate, sufficient reaction, appropriate primary particle size, and a loose silicon-titanium gel framework, facilitating pore expansion.

[0070] Compared to Example 1, Comparative Example 3, without the addition of amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, showed a decrease in pore volume, an increase in packing density, and a significant increase in particle size. The main reason is that the addition of amino-based silane coupling agents triggers a hydrolysis reaction, where the amino-containing organic groups replace the hydroxyl groups on the surface of the silicon-titanium composite, creating steric hindrance and preventing the compression of the pores, thereby increasing pore volume and reducing packing density. Secondly, the silane coupling agent can enhance the particle framework structure, preventing pore structure collapse, thus increasing the pore volume of the silicon-titanium composite and reducing its packing density.

[0071] Compared to Example 1, Comparative Example 4 differed in that the aging temperature was 90-100°C and the aging pressure was atmospheric pressure. The results showed that the sample pore volume decreased and the packing density increased. The main reason is that under high temperature and high pressure conditions and with the aid of silane coupling agent, the particles grew rapidly, resulting in a richly cross-linked silicon-titanium composite network structure, which increased the overall pore volume, strengthened stability, and decreased the packing density.

[0072] Compared with Example 1, Comparative Example 5 did not use 40°C hot pure water, 0.1% ammonium salt aqueous solution, and 40°C hot pure water in a washing sequence with time intervals of 2:5:3, and the washing time was 6 hours. Instead, it was directly washed with 40°C water for 6 hours. The results showed that the pore volume of the silicon-titanium composite decreased and the bulk density increased. The main ammonium salt released ammonia gas during the washing process, which could increase the pore volume of the silicon-titanium composite to a certain extent and reduce the bulk density, while other indicators remained almost unchanged.

[0073] Compared to Example 1, Comparative Example 6 used a common ceramic liner, and the results showed that the whiteness of the sample decreased and the particle size increased significantly. This is because the silicon-titanium composite has high hardness, with a Mohs hardness between 4 and 5, while common ceramic has a Mohs hardness of approximately 7-8. Prolonged pulverization with this ceramic results in wear, a short lifespan, and easy contamination of the material, leading to uneven particle size. This is inferior to alumina ceramic liners, zirconia ceramic liners, and zirconia-toughened alumina ceramic liners, which have a Mohs hardness of 8-10. Therefore, under the same pulverization pressure and fan frequency, the sample with the conventional pulverized structure has a higher particle size.

[0074] Application performance testing

[0075] The test mainly consists of two systems: a performance comparison test of single-layer thermal paper and a performance test of thermal paper with a bottom layer. Seven samples, including Examples 1, 3, and 5 prepared in this invention, Comparative Examples 2, 4, and 6, and Tosoh P527, were added as silica to the thermal paper performance system for application comparison.

[0076] I. Performance and Application Testing of Single-Layer Thermal Paper

[0077] Table 3. Thermal paper coating formulation

[0078] 2. Thermal paper making steps:

[0079] (1) Mix the required materials in the corresponding state according to the formula requirements. For the preparation of the dispersion, the materials should first be added to a 5wt% polyvinyl alcohol aqueous solution to prepare a 16.7wt% dispersion, and then wet-milled to a particle size of less than 3 micrometers before preparing a dispersion of the corresponding concentration.

[0080] (2) Disperse the prepared thermal paper coating in a disperser at a speed of 800~1000 rpm for 15 minutes, and test the viscosity after keeping it at 25℃;

[0081] (3) Apply the dispersed thermal paper coating to the paper using an air knife coating machine at a concentration of 5 g / m². 2 The coating amount is applied to the base paper;

[0082] (4) After the paint has dried, apply approximately 5 kg / cm² of water. 2 The roller pressure is used for calendering to improve its smoothness;

[0083] (5) Test the application performance of the treated thermal paper, including its glossiness, smoothness, whiteness, waste adhesion and printing characteristics.

[0084] 3. Physicochemical properties and application test results:

[0085] The performance test results of single-layer thermal paper for seven samples (Example 1, Example 3, Example 5, Comparative Example 2, Comparative Example 4, Comparative Example 6, and Tosoh P527) are shown in Table 4.

[0086] Product application testing methods and standards:

[0087] (1) Viscosity test: The viscosity of the coating was tested at 25°C using a rotational viscometer NDJ-5S with a #2 rotor;

[0088] (2) Gloss test: The gloss was tested using a BGD516 / 3 instrument with an incident angle of 60°. The larger the number, the worse the extinction.

[0089] (3) Buick smoothness test: According to the GB / T456-2002 test standard, the smoothness is measured using a Buick smoothness meter. The larger the number, the smoother the smoothness.

[0090] (4) Whiteness test: According to the ISO 11475 test standard, the CIE whiteness is measured using an X-Rite spectrophotometer. The larger the number, the higher the whiteness.

[0091] (5) Waste Adhesion Test: By setting the same printing length, observe the degree of printhead contamination after printing, with a range of 1-5, the higher the number, the more serious the contamination;

[0092] (6) Ink absorption: By setting the same print length pattern, observe the integrity of the printed paper pattern and whether there are white spots, broken lines, blurry phenomena, etc. The range is 1-5, and the larger the number, the worse the printing effect.

[0093] Table 4. Test results of physicochemical properties and thermal paper application performance of 7 samples.

[0094] II. Physical and chemical properties and application test results

[0095] Table 4 shows that the product provided in the examples exhibits relatively stable control over viscosity, gloss, whiteness, and smoothness in the application of thermal paper, with overall performance significantly better than the comparative example. It demonstrates better whiteness and smoothness, less waste residue, and better printing effect. Furthermore, the pore volume, bulk ratio, and particle size of the silicon-titanium composite for thermal paper are similar to those of the competitor Tosoh P527, with significantly improved whiteness and lower silica content. In terms of application performance testing, compared with the competitor Tosoh P527, the coating viscosity and smoothness are lower, while the viscosity, matting properties, and ink absorption are similar. However, the examples and comparative examples have lower overall viscosity and better dispersibility, resulting in better whiteness on thermal paper. Overall, the product performance is close to, or even better than, Tosoh P527.

[0096] The physicochemical indicators in the above six embodiments are only a portion of the embodiments, and only three embodiments and three comparative examples were selected for application performance testing and comparison with foreign competing products. However, it cannot be concluded that the specific implementation of this invention is limited to these examples and these application tests. Clearly, the above embodiments of this invention are merely examples to clearly illustrate the technical solution of this invention, and are not intended to limit the specific implementation of this invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of this invention should be included within the protection scope of the claims of this invention.

Claims

1. A method for preparing and using a silicon-titanium compound for thermal paper, characterized in that, It comprises the following steps: S1, preparing a water glass solution and a sulfuric acid solution; S2, adding the water glass solution into a reactor, then adding a titanyl sulfate solution to obtain a mixed solution and form a silicon-titanium gel; S3, fully stirring the silicon-titanium gel, maintaining pH, adding the water glass solution and the sulfuric acid solution, then adding an amino-type silane coupling agent, maintaining high temperature and high pressure aging, then adjusting pH to acidity to form a silicon-titanium precipitate, and aging to form a silicon-titanium compound; S4, washing the silicon-titanium compound with pure water, an ammonium salt aqueous solution, and pure water in sequence, drying, and then crushing with an airflow crusher to obtain the silicon-titanium compound.

2. The production method according to claim 1, characterized by, The modulus of the water glass in step S1 is 3.50-3.80, the concentration of silicon dioxide in the water glass solution is 5wt%-15wt%, and the concentration of the sulfuric acid solution is 5wt%-10wt%.

3. The preparation method according to claim 1, characterized in that, After adding the titanyl sulfate solution in step S2, the concentration of TiO2 in the mixed solution is 5wt%-10wt%, and the content of sulfuric acid in the mixed solution is 5wt%-10wt%.

4. The production method according to claim 3, characterized by, The amount of the water glass solution added in step S2 is 5%-20% of the total amount of the water glass, and the amount of the titanyl sulfate added satisfies the mass ratio of titanium to silicon of 1:(1-2).

5. The method of claim 1, wherein, The amino-type silane coupling agent added in step S3 is one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-ethyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and 3-aminopropylmethyldiethoxysilane, and the content is 1%-2% of the silicon-titanium compound.

6. The method of claim 1, wherein, In step S3, the silicon-titanium gel is fully stirred, and the pH is maintained at 8-11, the temperature of the temperature and pressure aging is 120-150℃, the pressure is 0.5-0.8MPa, and then the pH is adjusted to 2-4.

7. The preparation method according to claim 1, characterized in that, The washing in step S4 refers to washing with pure water, an ammonium salt aqueous solution, and pure water in sequence, with a washing time ratio of 2:5:3, until the conductivity of the silicon dioxide gel is less than 150μs / cm; the conductivity of the pure water is less than 5μs / cm, and the temperature is 40℃-70℃; the ammonium salt is one of ammonium sulfate, ammonium bisulfate, ammonium carbonate, or ammonium bicarbonate, and the mass concentration of the ammonium salt aqueous solution is 0.10%-0.50wt%.

8. The method of claim 1, wherein, The airflow crusher in step S4 is a fluidized bed airflow crusher with an alumina ceramic lining, a zirconia ceramic lining, or a zirconia toughened alumina ceramic lining.

9. A silicon-titanium compound for heat-sensitive paper prepared by the method of any one of claims 1-8.

10. The silicon titanium composite for thermal paper according to claim 9, characterized by, The whiteness of the heat-sensitive paper is 99.2% to 99.8%, the pore volume is 1.20cm 3 / g~1.50cm 3 / g, the bulk density is 0.30g / cm 3 ~0.40g / cm 3 The silicon dioxide content is 90% to 95%, the titanium element content is 4% to 8%, and the D50 particle size is 2.0~4.0 microns.

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