Halogen-free flame retardant for acrylic printing ink and preparation method of halogen-free flame retardant

Abstract

The invention relates to the technical field of flame-retardant ink, and discloses a halogen-free flame retardant for acrylic ink, the halogen-free flame retardant comprises the following components by weight: 0.5-3 parts of metal nitride; 1-4 parts of silicate or ceramic particles; 1-2 parts of a nano material; the invention further provides a preparation method of the halogen-free flame retardant for the acrylic ink, and the preparation method comprises the following steps: S1, solvent heat treatment: dispersing metal nitride, silicate or ceramic particles in an organic solvent, and carrying out a heating reaction; and S2, vapor deposition modification: performing deposition treatment on the nano material and organophosphate under a protective atmosphere. According to the preparation method disclosed by the invention, through dual surface modification, an optimized vapor deposition process and a fine crushing and screening technology, high dispersity, excellent thermal stability and uniform particle size distribution of the flame retardant are realized, so that the overall performance of the flame-retardant ink is improved.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant ink, in particular to a halogen-free flame retardant for acrylic ink and a preparation method thereof. Background Art

[0002] With the continuous development of electronic products, printing and packaging, and special functional coatings, the application demand for flame retardant inks is growing. Especially in circuit boards, flexible electronic components, and scenarios with high safety standards, flame retardant properties directly affect the reliability and service life of products. In order to meet these needs, flame retardant inks need to have excellent thermal stability, uniform dispersion, and good processing adaptability.

[0003] At present, common flame retardant modification technologies mainly rely on a single surface modifier to improve the compatibility of flame retardants with inks. Such methods can improve the wettability of flame retardants in inks to a certain extent, making them easier to disperse and improving the flame retardant effect. At the same time, the thermal stability of flame retardants is usually enhanced by vapor deposition or surface coating to reduce decomposition under high temperature conditions. In addition, the particle size control of flame retardants mainly uses ball milling or mechanical crushing technology to make the flame retardant reach a more ideal fineness to adapt to different types of ink systems. These technologies have improved the applicability of flame retardant inks to a certain extent, making them widely used in printing, circuit coating and other fields.

[0004] Although the existing technology has made certain progress in improving the performance of flame retardant inks, there are still some shortcomings; first, the use of a single surface modifier fails to fully improve the dispersion effect of the flame retardant, and the particles are still easy to agglomerate, affecting the uniformity of the ink; second, the existing vapor deposition modification temperature is relatively low, resulting in limited improvement in the heat resistance of the flame retardant, and it is difficult to fully improve the high-temperature stability of the ink; thirdly, the particle size control of the traditional pulverization method is not precise enough, and some particles are too large and easy to settle, affecting the dispersion uniformity and long-term storage stability of the ink; in addition, the process that relies solely on the high-speed dispersion method still has the problem of particle aggregation during the dispersion of the flame retardant, which makes the viscosity of the ink fluctuate greatly, affecting the final coating and flame retardant effect. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a halogen-free flame retardant for acrylic ink and a preparation method thereof, which solves the problems of uneven dispersion of the flame retardant, insufficient thermal stability and inaccurate particle size control.

[0006] To achieve the above object, the present invention is implemented by the following technical scheme: a halogen-free flame retardant for acrylic ink, the halogen-free flame retardant comprising the following components in parts by weight: Metal nitride: 0.5-3 parts. The high thermal stability of metal nitride can effectively prevent the flame from being transmitted to the substrate, thus providing a thermal barrier effect. At the same time, metal nitride can inhibit the generation of harmful gases during the combustion process by reacting with oxygen or other gases at high temperatures, thereby reducing the possibility of flame spread; Silicate or ceramic particles: 1-4 parts. Ceramic particles can provide effective thermal isolation under flames through their low thermal conductivity. By reducing the conduction of heat to the acrylic ink matrix, the thermal decomposition rate of the ink is reduced. Under high temperature conditions, ceramic particles can react with oxygen to form a stable high-temperature resistant film to prevent the flame from further extending to the matrix. The chemical reactivity of silicate materials also helps to absorb part of the heat or form a chemical barrier during the fire, thereby reducing the spread of flames. Nanomaterials: 1-2 parts. Since nanomaterials have a large specific surface area, their dispersibility in the ink matrix is ​​very high. This high surface area can enhance the compatibility of flame retardants with the ink matrix and promote uniform dispersion. Nanomaterials have strong thermal stability at high temperatures, can exist stably in flames, and reduce heat conduction through thermal barrier effects. Organic phosphate ester: 2-4 parts. Organic phosphate ester can decompose at high temperature and release expansive gas. These gases will promote the formation of an expansive carbonized layer on the surface of the ink, thereby preventing the spread of flames. During a fire, organic phosphate ester can inhibit the generation of free radicals in the combustion reaction by generating compounds such as phosphates or phosphate esters, thereby slowing down the combustion rate. Carbon former: 1-3 parts. Carbon former will decompose under high temperature conditions, releasing expansive gas and forming a stable carbonized layer. This carbonized layer can effectively isolate oxygen and thus inhibit the spread of flames.

[0007] Preferably, the metal nitride comprises: Aluminum nitride: 0.2-1.5 parts. Aluminum nitride has a high thermal conductivity, which allows it to quickly disperse heat to the surrounding environment when the flame contacts the ink matrix, thereby reducing the impact of the flame on the matrix and delaying the combustion process of the ink. Aluminum nitride has a high decomposition temperature and can exist stably at high temperatures and is not easy to decompose. It can provide the necessary thermal barrier for the ink, reduce the decomposition and combustion reactions under high temperature conditions, and can react chemically with moisture and oxygen in the air to generate stable aluminum oxides or nitrides. These products have an effective inhibitory effect on the flame; Silicon nitride: 0.1-1 parts. Silicon nitride's high melting point and excellent thermal stability allow it to withstand high temperatures without decomposing or melting, which allows it to remain stable and act as a thermal barrier when a fire occurs, while limiting the spread of flames through its physical barrier effect. The presence of silicon nitride can reduce the contact between the flame and the substrate and reduce the combustion rate. Silicon nitride is not only resistant to high temperatures, but also has good oxidation resistance, which can prevent the reaction of oxygen with the burning substance and further inhibit the spread of flames; Boron nitride: 0.2-0.8 parts. Boron nitride is a material with high thermal conductivity and thermal stability. With high thermal conductivity, it can quickly disperse the heat released by the flame to the surrounding environment, thereby reducing the spread of the flame. This allows boron nitride to effectively isolate the fire source and protect acrylic ink from the direct impact of high temperature. The presence of boron nitride helps to form a carbonized layer during the combustion process. This carbonized layer can reduce the entry of oxygen and slow down the spread of the flame.

[0008] Preferably, the silicate or ceramic particles include: Aluminum titanate: 0.5-2.5 parts. Aluminum titanate is an inorganic compound that is stable at high temperatures and has low thermal conductivity. It can form a barrier at high temperatures to slow down the transfer of heat to the ink matrix and prevent excessive heat from causing further decomposition or combustion of the ink. Its thermal isolation effect is crucial to improving the thermal stability and flame resistance of the ink. Under high temperature conditions, aluminum titanate can react with oxygen in the air to form a protective film, reducing the damage of oxygen to the ink matrix, thereby inhibiting the combustion of the ink; Aluminum silicate: 0.3-1.5 parts. Aluminum silicate is another inorganic material commonly used in high-temperature applications. It has high thermal stability and can effectively maintain its physical structure at high temperatures. It can form a heat-insulating layer under flame conditions, reduce the thermal impact of flames on the ink, and reduce the decomposition rate of the ink. When the flame contacts the ink, it can provide an effective physical barrier through its high temperature resistance and low thermal conductivity to prevent the spread of the flame. At the same time, it will not react violently with external environments such as oxygen and moisture at high temperatures, ensuring that it still maintains good chemical stability under extreme conditions; Zirconium silicate: 0.2-1 part. Zirconium silicate is a high temperature resistant inorganic compound that can withstand extremely high temperatures and has low thermal conductivity. When exposed to flames, it can effectively slow down the conduction of heat to the ink matrix, thereby providing effective thermal protection for the ink. At the same time, it can maintain a stable structure in the flame, further reducing the burning rate and decomposition rate of the ink.

[0009] Preferably, the nanomaterial comprises: Nano silicon: 0.5-1 part. Nano silicon is an inorganic material with a very high surface area and good thermal stability. Since nano silicon has a very large specific surface area, it can form a stronger interface with the ink matrix, thereby improving the dispersion of the flame retardant in the ink, ensuring that the flame retardant is evenly distributed in the ink, avoiding precipitation or stratification. It can effectively inhibit the thermal degradation of the ink matrix at high temperature, reduce the release of harmful gases at high temperature, and thus improve the thermal stability of the ink; Nano-alumina: 0.3-0.8 parts. Nano-alumina is a common inorganic nano-material with excellent chemical stability at high temperatures. It will not decompose or melt, thus maintaining its physical structure in a high-temperature fire environment, providing a continuous flame retardant effect. It can also resist the erosion of oxygen and moisture, preventing the ink matrix from being affected by oxidation reactions in a fire, thereby further reducing the release of harmful gases in a fire; Nanocarbon: 0.2-0.7 parts. Nanocarbon material is a material with very high surface area and conductivity. It can react with the ink matrix at high temperature to promote the formation of a surface carbonization layer. The carbonization layer can effectively isolate oxygen, reduce oxidation reactions, and thus slow down the combustion rate. It can also further increase the shielding effect on heat by forming a structured carbon layer, preventing the flame from spreading to the matrix. Under high temperature conditions, nanocarbon can stabilize the carbonization layer, inhibit the release of harmful gases such as carbon monoxide and carbon dioxide, and reduce the pollution to the environment in the fire.

[0010] The present invention also provides a method for preparing a halogen-free flame retardant for acrylic ink, comprising the following steps: S1. Solvent thermal treatment: metal nitride, silicate or ceramic particles are dispersed in an organic solvent and heated for reaction. The organic solvent provides a mild environment that can promote the reaction between metal nitride and silicate or ceramic particles. By heating, the reaction temperature increases, the reaction rate accelerates, and it is conducive to the interaction between substances to form a stable composite material; S2, vapor deposition modification, the nanomaterials and organic phosphates are deposited under a protective atmosphere. The vapor deposition process can evenly deposit the organic phosphates on the surface of the nanomaterials. This process can not only improve the compatibility of the nanomaterials with the ink matrix, but also improve the functionalization effect of the flame retardant. Under a protective atmosphere, the deposition process can ensure the chemical reaction between the organic phosphate and the nanomaterials. Through this modification, the surface properties of the nanomaterials are improved, making them have better flame retardancy and compatibility with the ink matrix; S3, surface functionalization treatment, modifying the surface polar groups of the flame retardant to make it dispersible, and improving the hydrophilicity or lipophilicity of the flame retardant surface by introducing polar groups (such as amino, carboxyl, etc.), thereby improving its compatibility with the acrylic ink matrix. This polar group can enhance the interaction with the ink molecules and promote uniform dispersion; S4, drying and crushing, the treated material is dried and crushed to the desired particle size range. The drying step can remove the solvent and moisture to avoid the residual solvent affecting the quality and effect of the flame retardant. By crushing, the particle size of the flame retardant can be controlled within the appropriate range. Smaller particle size can increase the specific surface area, improve the activity and dispersibility of the flame retardant, thereby improving the flame retardant performance and compatibility with ink.

[0011] Preferably, the solvent thermal treatment comprises: Dichloromethane or dimethyl sulfoxide is selected as the solvent. Dichloromethane has good solubility and can effectively dissolve and disperse metal nitrides, silicates or ceramic particles. Its high volatility is conducive to the rapid removal of the solvent by heating and centrifugal separation after the reaction; while methyl sulfoxide has extremely high solubility and is particularly suitable for dissolving highly polar or difficult to dissolve substances. In addition, its high boiling point and low volatility ensure that the solvent can be maintained under suitable reaction conditions during the solvent thermal treatment process; Stir the reaction at a temperature of 160-200°C for 2-4 hours. Increasing the temperature can increase the kinetic energy of the reactants, accelerate the dissolution and reaction of the metal nitride and silicate particles, and effectively promote the reaction, so that these particles and other components fully react to form a precursor of the composite flame retardant. At the same time, during the solvent thermal treatment process, the solvent can help the metal nitride and other components to be evenly dispersed and avoid aggregation between particles. High temperature conditions help to accelerate the interaction between the solvent and the solute, ensure good dispersion of the reactants, and avoid crystallization or agglomeration. The solvent is removed by centrifugal separation to obtain a preliminarily dispersed composite flame retardant precursor. Centrifugal separation can effectively remove solvents such as dichloromethane or dimethyl sulfoxide, leaving the composite flame retardant precursor formed by the reaction. At the same time, the reactants can be concentrated so that the formed composite material is more evenly distributed under the action of centrifugal force, avoiding precipitation or stratification of the material.

[0012] Preferably, the vapor deposition modification comprises: The deposition reaction is carried out in an argon, nitrogen or hydrogen atmosphere. Argon, as an inert gas, does not participate in chemical reactions. Its main function is to provide an inert environment to avoid oxidation of the deposited material at high temperatures. Argon can ensure that the material does not react with oxygen during the deposition process, thereby avoiding the formation of oxides or other unnecessary compounds; nitrogen is an inert gas that is often used to prevent the formation of peroxides, especially when the reactants contain some easily oxidizable components. It can effectively protect the deposited material and promote the desired chemical reaction without introducing impurities; hydrogen is not only an inert gas in the vapor deposition process, but can also participate in certain chemical reactions, especially reduction reactions. When the deposited material needs to be reduced, hydrogen is one of the ideal atmospheres; The reaction temperature is controlled at 600-800°C. At 600°C, the deposition reaction can proceed more rapidly, and the reactant molecules have higher kinetic energy in the gas phase, so they can be quickly deposited on the surface of the substrate material. At 800°C, the reactant molecules in the gas phase are more easily activated and can effectively react with the surface of the deposition material to form a uniform coating. When the temperature is less than 600°C, it is easy to cause an incomplete deposition process, forming an uneven coating or a low efficiency of the decomposition reaction. The reaction time is controlled within 1-2 hours to ensure uniform deposition of the material. Too short a reaction time will result in uneven or incomplete deposition, while too long a reaction time will result in overreaction, forming undesirable byproducts or affecting the quality of the deposited layer. Therefore, controlling the reaction time within 1-2 hours can effectively prevent overdeposition or incomplete reaction.

[0013] Preferably, the surface functionalization treatment includes: Aminosilane or carboxyl modifier is used for surface treatment. Aminosilane is a chemical reagent containing amino and silane groups, which has strong hydrophilicity and good reactivity. In the surface functionalization treatment, aminosilane can chemically react with the surface of the flame retardant to generate a surface with amino groups. The amino group can enhance the interaction between the flame retardant and the polar molecules in the acrylic ink, thereby improving its dispersibility and compatibility; carboxyl modifier is another commonly used surface modifier, which can react with the flame retardant surface through the carboxyl group to make the surface have hydrophilic or polar groups. This polar group can increase the affinity of the flame retardant with the polar components in the ink, thereby promoting uniform dispersion, improving the stability of the ink and the final flame retardant effect; The treatment temperature is controlled at 40-60℃. If the temperature is too low, the rate of the surface modification reaction is likely to be too slow, and the surface modification cannot be completed within the specified time, so the ideal modification effect cannot be achieved. Too high a temperature will cause the modifier to decompose or induce side reactions, and even make the surface modification uneven, affecting the performance of the final flame retardant. By controlling the temperature within the range of 40-60℃, it can ensure the efficient progress of the modification reaction and avoid the occurrence of side reactions and over-reactions, thereby obtaining the best modification effect; The treatment time is 1-2 hours to enhance the polar compatibility of the flame retardant. If the reaction time is less than 1 hour, the modifier may fail to completely react with the surface of the flame retardant, resulting in insufficient surface modification, affecting the dispersibility and compatibility of the flame retardant, and failing to effectively improve the flame retardant effect. If the reaction time is more than 2 hours, it may easily lead to side reactions or make the concentration of the modifier too high, thereby affecting other properties of the flame retardant, such as hardness or stability. Therefore, the reaction time within this range can ensure that the modifier reacts completely with the surface of the flame retardant while avoiding excessive reaction.

[0014] Preferably, the drying and pulverizing comprises: Drying at 60-80℃ to remove residual solvents. Drying at a temperature range of 60-80℃ can not only effectively remove solvents, but also avoid thermal degradation of flame retardants at high temperatures. Excessive temperatures can cause decomposition or other chemical changes in flame retardants, affecting their performance. This temperature range provides a mild heat treatment environment, ensuring effective removal of solvents while maintaining the structure and performance of flame retardants. Use an air flow mill or ball mill to crush the particles to a particle size range of 0.5-5μm. The air flow mill uses a high-speed air flow to accelerate the particles to a high speed, so that the materials collide with each other and crush in the air flow. This equipment can achieve a high crushing efficiency, and because it does not require mechanical pressure, it reduces mechanical damage to the material and helps maintain the structural stability of the flame retardant. The air flow mill is suitable for processing brittle materials and can efficiently crush the materials to the micron level. The ball mill is a device that crushes materials by grinding with balls. The friction and collision of the balls in the grinding tank crush the materials into fine particles. The crushing effect of the ball mill is relatively stable, suitable for different types of materials, and can achieve precise particle size control. When using a ball mill, the flame retardant particles are ground into smaller particle sizes to ensure their uniform dispersion in the ink matrix; The final flame retardant powder with uniform particle size is obtained by screening. Screening helps to remove particles that are too large or too small, so as to obtain a uniform product that meets the specifications. The flame retardant with uniform particle size obtained after screening can be better dispersed in the ink matrix to avoid particle agglomeration, ensuring that the ink is stable during use and that the flame retardant properties are fully exerted.

[0015] Preferably, the flame retardant is finally used in the acrylic ink in the following manner: The flame retardant is added to the ink matrix through the high-speed dispersion method. The high-speed rotating agitator causes the flame retardant particles to collide and rub strongly in the liquid, thereby helping the particles to be fully dispersed in the liquid, overcoming the electrostatic attraction and cohesion between the particles. Through the action of this high shear force, the flame retardant particles can quickly break the agglomeration state and disperse into the liquid, avoiding the precipitation and agglomeration of large particles. Flame retardants with smaller particle size and uniform dispersion can ensure better performance in inks, especially in terms of improving flame retardancy and uniform coating; Ultrasonic oscillation technology is used to further evenly disperse. When ultrasonic oscillates, tiny bubbles formed in the liquid expand and collapse rapidly, producing strong local temperature and pressure changes. This phenomenon is called cavitation effect. The cavitation effect can generate a strong force field to help the flame retardant particles further disperse, break the aggregation between particles, and promote their uniform dispersion in the ink. Ultrasonic oscillation also induces local high-speed shear force in the liquid through the rapid collapse of the tiny bubbles generated, further strengthening the dispersion effect on the flame retardant particles. This process can effectively remove the aggregates of flame retardant particles and make the particles more evenly distributed in the ink; A filter device is used to remove undispersed particles to ensure the stability of the ink. After the flame retardant is treated by high-speed dispersion and ultrasonic oscillation, some large particles that are not completely dispersed are likely to remain. These large particles will cause uneven particles or precipitation during the coating and use of the ink, affecting the flame retardant effect and the quality of the ink. Therefore, through the precise screening of the filter device, the missed large particles can be effectively removed, thereby improving the stability of the ink. Uniform ink can not only provide better gloss, but also ensure the quality of the coating, reduce the uneven phenomenon during the coating process, and avoid the roughness of the ink surface.

[0016] The present invention provides a halogen-free flame retardant for acrylic ink and a preparation method thereof. The invention has the following beneficial effects: 1. The present invention uses aminosilane and carboxyl modifiers together to greatly improve the compatibility of flame retardants and acrylic inks. Compared with the use of a single modifier in the traditional method, the present invention solves the problem of easy aggregation of flame retardants in inks, ensures that the ink does not stratify for a long time, and enhances stability and dispersibility.

[0017] 2. By adopting vapor deposition modification technology, the reaction process is precisely controlled at high temperature, and the high temperature resistance of the flame retardant is significantly improved. Compared with the existing traditional surface treatment methods, the present invention is better in improving the flame retardant effect and thermal stability, and solves the problems of decomposition and performance degradation during the use of ink.

[0018] 3. The present invention combines ultrasonic oscillation technology and high-speed dispersion method to make the dispersion of flame retardant in ink more delicate and uniform. Different from the technology that relies solely on high-speed dispersion, this dual dispersion method solves the problem of particle aggregation, making the dispersion effect of ink more ideal and the flame retardant performance more outstanding.

[0019] 4. Use air flow mill and screening process to accurately control the consistency of flame retardant particle size. This is more efficient than the traditional ball mill crushing and non-screening method, avoiding the existence of uneven particles, optimizing the coating and stability of the ink, and improving the overall flame retardant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please refer to the attached Figure 1 : Example 1 step: Prepare the materials: Select 5 parts each of aminosilane modifier and carboxyl modifier.

[0023] 30 parts of nano-grade halogen-free flame retardant are selected.

[0024] Prepare 100 parts of acrylic ink matrix.

[0025] Surface modification: Add the aminosilane modifier and the carboxyl modifier into the nano flame retardant and stir evenly.

[0026] Stir at 40°C for 2 hours to ensure that the modifier reacts fully with the surface of the flame retardant.

[0027] Vapor deposition modification: The vapor deposition process was carried out in an argon atmosphere, the temperature was set at 750° C., and the reaction time was 1 hour.

[0028] Ensure that the material is evenly deposited on the surface of the flame retardant under reaction conditions to enhance high temperature resistance and flame retardancy.

[0029] Drying and crushing: The flame retardant modified by vapor deposition was dried at 60° C. to remove the residual solvent.

[0030] Use a jet mill to grind the particles and control the particle size within 3 μm.

[0031] The unqualified particles are removed through the screening device to obtain the final uniformly dispersed flame retardant powder.

[0032] Add ink: The treated flame retardant is added to the ink matrix using a high speed dispersion method.

[0033] Ultrasonic oscillation technology is used to ensure that the flame retardant is completely and evenly dispersed.

[0034] Finally, a filtration device is used to remove undispersed particles to ensure ink stability.

[0035] Example 2 step: Prepare the materials: 3 parts of hydroxysilane modifier and 2 parts of phenyl modifier.

[0036] 20 parts of nano halogen-free flame retardant.

[0037] Acrylic ink base 150 parts.

[0038] Surface functionalization: At 40°C, hydroxysilane and phenyl modifier were mixed and added to the nano flame retardant, and stirred for reaction for 2 hours to fully combine them.

[0039] After completion, continue stirring at 70°C for 1 hour to ensure uniform modification.

[0040] Vapor Deposition: The vapor deposition process was carried out in a nitrogen atmosphere, the temperature was controlled at 700° C., and the reaction time was set to 1.5 hours.

[0041] Ensure uniform deposition of materials and improve their heat resistance and flame retardant properties.

[0042] Drying and crushing: The vapor deposited flame retardant was dried at 75°C to remove the residual solvent.

[0043] Use a ball mill to grind to a particle size of 2 μm to ensure uniform particle refinement.

[0044] The particles that do not meet the specifications are removed through the screening device to ensure that the final powder is uniform.

[0045] Add to ink: The treated flame retardant is added to the acrylic ink matrix by a high-speed dispersion method.

[0046] Ultrasonic vibration technology is used to further evenly disperse the ink to ensure that the particles do not aggregate.

[0047] Use filtration equipment to remove incompletely dispersed particles and keep the ink stable.

[0048] Example 3 step: Prepare the materials: 6 parts of aminosilane modifier and 4 parts of carboxyl modifier.

[0049] 40 parts of nano halogen-free flame retardant.

[0050] Acrylic ink base 120 parts.

[0051] Surface treatment: The aminosilane and the carboxyl modifier are added into the nano halogen-free flame retardant according to a proportion.

[0052] Stir at 60 °C for 3 h to ensure uniform surface reaction.

[0053] Vapor Deposition: Vapor deposition was carried out in an argon atmosphere, the temperature was set at 800° C., and the reaction time was controlled to be 1 hour.

[0054] Ensure uniform deposition of flame retardant on the surface to improve its thermal stability and flame retardant properties.

[0055] Drying and crushing: The drying temperature was 70°C for 3 hours to remove all residual solvent.

[0056] The powder was crushed using a jet mill and the particle size was controlled at about 0.8 μm.

[0057] By screening, unqualified particles are removed to ensure that uniform flame retardant powder is obtained in the end.

[0058] Add ink: The treated flame retardant is added to the ink matrix using a high-speed dispersion method.

[0059] Ultrasonic vibration further disperses the ink evenly, ensuring that there is no particle aggregation in the ink.

[0060] Finally, a filtration device is used to remove undispersed particles to ensure ink stability.

[0061] Example 4 step: Prepare the materials: 8 parts of aminosilane modifier.

[0062] 25 parts of halogen-free flame retardant.

[0063] Acrylic ink base 180 parts.

[0064] Surface modification: The aminosilane modifier and the halogen-free flame retardant were mixed, stirred for 2 hours, and reacted at 50°C.

[0065] After surface modification, the film was dried at 80°C for 1 hour.

[0066] Vapor Deposition: Vapor deposition was carried out under a nitrogen atmosphere with the temperature set to 725 °C and the reaction time set to 1 h to ensure uniform modification.

[0067] Drying and crushing: The drying temperature was set at 65°C to remove all solvents.

[0068] The particles were crushed to a particle size of 1 μm using a ball mill.

[0069] The flame retardant powder with uniform particle size is obtained by sieving.

[0070] Add ink: The treated flame retardant is added to the ink matrix using a high speed dispersion method.

[0071] Ultrasonic vibration technology is used to disperse particles evenly and avoid particle aggregation.

[0072] Use filtration to remove undispersed particles and ensure ink stability.

[0073] Comparative Example 1: Prior art: Using a single aminosilane modifier to modify the surface of a flame retardant.

[0074] Comparative Example Steps: Prepare the materials: Select 10 parts of aminosilane modifier.

[0075] 30 parts of nano-grade halogen-free flame retardant.

[0076] Acrylic ink base 100 parts.

[0077] Surface modification: Add the aminosilane modifier into the nano flame retardant, stir evenly, and keep the reaction at 50°C for 2 hours.

[0078] This treatment used only a single modifier and no carboxyl modifier.

[0079] Vapor deposition modification: Vapor deposition was carried out under argon atmosphere at 750 °C and reaction time of 1 h to ensure uniform deposition.

[0080] Drying and crushing: Dry at 60°C for 2 hours to remove residual solvent.

[0081] The powder was crushed using a jet mill and the particle size was within 3 μm.

[0082] By screening, unqualified particles are removed to ensure the uniformity of the final flame retardant powder.

[0083] Add to ink: The flame retardant is added to the ink using a high speed dispersion method.

[0084] Ultrasonic vibration technology is used to further disperse it evenly.

[0085] Use filtration equipment to remove undispersed particles to ensure the stability of the ink.

[0086] Comparative Example 2: Existing technology: The flame retardant is dispersed by a traditional high-speed dispersion method without combining ultrasonic oscillation technology.

[0087] Comparative Example Steps: Prepare the materials: 2 parts of hydroxysilane modifier and 2 parts of phenyl modifier.

[0088] 20 parts of nano halogen-free flame retardant.

[0089] Acrylic ink base 150 parts.

[0090] Surface functionalization: The hydroxy silane and the phenyl modifier were mixed and added into the nano flame retardant, and stirred for reaction at 50° C. for 2 hours.

[0091] This step does not involve the use of ultrasonic vibration technology.

[0092] Vapor Deposition: The vapor deposition was carried out in a nitrogen atmosphere, the temperature was controlled at 700° C., and the reaction time was 1.5 hours.

[0093] Drying and crushing: Dry at 75°C for 2 hours to remove residual solvent.

[0094] The resulting product was pulverized using a ball mill to a particle size of 2 μm.

[0095] The flame retardant powder with uniform particle size is obtained by sieving.

[0096] Add to ink: The treated flame retardant is added to the ink using a high speed dispersion method.

[0097] No ultrasonic vibration, direct dispersion.

[0098] Comparative Example 3: Existing technology: A single vapor deposition process is used to modify the flame retardant, and the crushing process is relatively simple, and the particle size is not precisely controlled.

[0099] Comparative Example Steps: Prepare the materials: 6 parts of aminosilane modifier.

[0100] 40 parts of halogen-free flame retardant.

[0101] Acrylic ink base 120 parts.

[0102] Surface modification: The aminosilane modifier and the halogen-free flame retardant were mixed, stirred for 2 hours, and reacted at 50°C.

[0103] No carboxyl modifier was used in the modification step.

[0104] Vapor Deposition: The vapor deposition was carried out in an argon atmosphere, the temperature was controlled at 800°C, the reaction time was 1 hour, and the film was deposited on the surface of the flame retardant.

[0105] Drying and crushing: Dry at 70°C for 2 hours to remove residual solvent.

[0106] The product was pulverized using a ball mill to a particle size of 2 μm without sieving.

[0107] Add to ink: The flame retardant is added to the ink by a high-speed dispersion method.

[0108] Comparative Example 4: Existing technology: adopts traditional surface modification method and vapor deposition process, without further optimizing drying and pulverizing process, and without precise control of particle size distribution.

[0109] Comparative Example Steps: Prepare the materials: 8 parts of aminosilane modifier.

[0110] 25 parts of halogen-free flame retardant.

[0111] Acrylic ink base 180 parts.

[0112] Surface modification: The aminosilane modifier and the halogen-free flame retardant were mixed and stirred at 60° C. for 2 hours to perform surface modification.

[0113] Vapor Deposition: Vapor deposition was carried out in an argon atmosphere, the temperature was set to 725°C, and the reaction time was 1 hour.

[0114] Drying and crushing: Dry at 65°C for 3 hours to remove all solvents.

[0115] The powder was crushed using a jet mill, and the particle size range was about 3 μm, without further screening.

[0116] Add to ink: The flame retardant is added to the ink using a high-speed dispersion method.

[0117] Comparative experiment: Experiment on the influence of surface modifiers Experimental Materials: Aminosilane modifier, carboxyl modifier, nano halogen-free flame retardant, acrylic ink matrix Experimental steps: The raw materials required for Example 1 and Comparative Example 1 were taken respectively: Example 1 used aminosilane and carboxyl modifier (5 parts each), and Comparative Example 1 used only aminosilane modifier (10 parts).

[0118] The surface modifier was added to the nano flame retardant and stirred at 40° C. for 2 hours to complete the surface functionalization.

[0119] The modified flame retardant was subjected to vapor deposition: Example 1 was treated at 750°C for 1 hour, and Comparative Example 1 was treated at 750°C for 1 hour.

[0120] After drying and crushing (air flow mill) to 3μm, sieving is performed to ensure the uniformity of the final flame retardant powder.

[0121] The treated flame retardant is added into the ink matrix and evenly dispersed using high-speed dispersion method and ultrasonic oscillation technology.

[0122] Experimental study on the effect of ultrasonic oscillation technology on the dispersion of flame retardants Experimental Materials: Aminosilane modifier, carboxyl modifier, nano halogen-free flame retardant, acrylic ink matrix Experimental steps: Take the raw materials of Example 2 (using high-speed dispersion method and ultrasonic oscillation technology) and the raw materials of Comparative Example 2 (using only high-speed dispersion method).

[0123] The surface-modified flame retardant was added into the ink matrix and further evenly dispersed using ultrasonic oscillation technology (frequency 40 kHz, power 150 W).

[0124] The control group used only the high-speed dispersion method without ultrasonic oscillation technology.

[0125] The viscosity of the ink was tested separately, the dispersion effect was observed using a microscope, and the particle size and uniformity were analyzed.

[0126] Experimental study on the effect of vapor deposition process on the thermal stability of flame retardants Experimental Materials: Aminosilane modifier, nano halogen-free flame retardant, acrylic ink matrix Experimental steps: According to the schemes of Example 3 and Comparative Example 3, a surface-modified flame retardant was prepared (Example 3 was vapor-deposited at 750° C. for 1 hour; Comparative Example 3 was vapor-deposited at 700° C. for 1 hour).

[0127] Drying (2 hours at 60°C) and pulverization (to 2 μm) were performed.

[0128] The thermal stability of the flame retardant was tested using a thermogravimetric analyzer (TGA), and the thermal degradation temperature and residue ratio were recorded.

[0129] The flame retardant effect of ink is tested using the UL-94 combustion test method.

[0130] Experiment on the effect of crushing process on the distribution of flame retardant particles Experimental Materials: Aminosilane modifier, halogen-free flame retardant, acrylic ink matrix Experimental steps: The pulverization process of Example 4 and Comparative Example 4 was used. In Example 4, the flame retardant was pulverized to 1 μm using a jet mill and used after sieving; in Comparative Example 4, the flame retardant was pulverized to 2 μm using a ball mill without sieving.

[0131] The crushed flame retardant is added to the ink matrix and dispersed using a high-speed dispersion method.

[0132] Use a microscope to observe the particle distribution in the ink and record the uniformity of the particles.

[0133] A stability test was conducted to observe the stratification of the ink after it was left to stand for 48 hours.

[0134] Experimental data comparison table: Parameter comparison between examples and comparative examples From the above table, we can get: First, by using aminosilane and carboxyl modifiers for combined surface modification, Example 1 significantly improves the compatibility and dispersibility of the flame retardant. Compared with the application of a single modifier in Comparative Example 1, the particle distribution in the ink is more uniform, and the stability and flame retardant performance are greatly improved. This shows that the combined use of surface modifiers can effectively overcome the shortcomings of a single modifier, optimize the performance of the flame retardant, and improve the application effect of the ink.

[0135] Secondly, Example 2 further improves the dispersibility of the flame retardant in the ink by combining the ultrasonic oscillation technology. Compared with Comparative Example 2 which only uses the high-speed dispersion method, the particle distribution of the ink is more uniform and the dispersion effect is better. The ultrasonic oscillation technology can provide a more detailed dispersion effect, avoid the agglomeration and precipitation of particles, and improve and enhance the stability and life of the ink.

[0136] Finally, the temperature control of the vapor deposition process plays a key role in the thermal stability and flame retardant performance of the flame retardant. The vapor deposition temperature of 750°C in Example 3 significantly improved the thermal stability of the flame retardant. Compared with the temperature of 700°C in Comparative Example 3, the thermal degradation temperature and residue ratio of the flame retardant were better. This shows that appropriately increasing the vapor deposition temperature can optimize the thermal stability of the flame retardant and improve the flame retardant effect of the ink.

[0137] In terms of the pulverizing process, Example 4 uses a jet mill and a screening step to finely control the particle size, ensuring the uniform distribution of the flame retardant in the ink, while Comparative Example 4 uses a ball mill for pulverization without screening, resulting in uneven distribution of particles, thereby affecting the stability and flame retardant properties of the ink.

[0138] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A halogen-free flame retardant for acrylic ink, characterized in that: The halogen-free flame retardant comprises the following components in parts by weight: Metal nitride: 0.5-3 parts; Silicate or ceramic particles: 1-4 parts; Nanomaterials: 1-2 parts; Organic phosphate: 2-4 parts; Carbon-forming agent: 1-3 parts.

2. The halogen-free flame retardant for acrylic ink according to claim 1, characterized in that: The metal nitride comprises: Aluminum nitride: 0.2-1.5 parts; Silicon nitride: 0.1-1 part; Boron nitride: 0.2-0.8 parts.

3. The halogen-free flame retardant for acrylic ink according to claim 1, characterized in that: The silicate or ceramic particles include: Aluminum titanate: 0.5-2.5 parts; Aluminum silicate: 0.3-1.5 parts; Zirconium silicate: 0.2-1 part.

4. The halogen-free flame retardant for acrylic ink according to claim 1, characterized in that: The nanomaterials include: Nano silicon: 0.5-1 part; Nano-alumina: 0.3-0.8 parts; Nanocarbon: 0.2-0.7 parts.

5. A method for preparing a halogen-free flame retardant for acrylic ink, characterized in that: Using the halogen-free flame retardant for acrylic ink according to any one of claims 1 to 4 comprises the following steps: S1, solvent thermal treatment, dispersing metal nitride, silicate or ceramic particles in an organic solvent and heating them for reaction; S2, vapor deposition modification, depositing the nanomaterials and organic phosphates under a protective atmosphere; S3, surface functionalization treatment, modifying the surface polar groups of the obtained flame retardant to make it dispersible; S4, drying and crushing, drying and crushing the processed material to a desired particle size range.

6. The method for preparing a halogen-free flame retardant for acrylic ink according to claim 5, characterized in that: The solvent thermal treatment comprises: Select dichloromethane or dimethyl sulfoxide as solvent; Stir the reaction at 160-200°C for 2-4 hours; The solvent is removed by centrifugal separation to obtain a preliminarily dispersed composite flame retardant precursor.

7. The method for preparing a halogen-free flame retardant for acrylic ink according to claim 5, characterized in that: The vapor deposition modification comprises: The deposition reaction is carried out under an argon, nitrogen or hydrogen atmosphere; The reaction temperature is controlled at 600-800°C; The reaction time is controlled within 1-2 hours to ensure uniform deposition of the material.

8. The method for preparing a halogen-free flame retardant for acrylic ink according to claim 5, characterized in that: The surface functionalization treatment comprises: Surface treatment with aminosilane or carboxyl modifiers; The processing temperature is controlled at 40-60℃; The treatment time is 1-2 hours to enhance the polar compatibility of the flame retardant.

9. The method for preparing a halogen-free flame retardant for acrylic ink according to claim 5, characterized in that: The drying and pulverizing comprises: Drying at 60-80°C to remove residual solvent; Use a jet mill or ball mill to grind to a particle size range of 0.5-5μm; The final flame retardant powder with uniform particle size is obtained by sieving.

10. The method for preparing a halogen-free flame retardant for acrylic ink according to claim 9, characterized in that: The flame retardant is finally used in acrylic ink in the following ways: The flame retardant is added to the ink matrix by a high-speed dispersion method; Ultrasonic oscillation technology is used to further disperse evenly; A filtration device is used to remove undispersed particles to ensure the stability of the ink.

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