Printing ink for thin film pressure sensor and preparation method thereof

Abstract

The invention discloses printing ink for a film pressure sensor and a preparation method thereof, and relates to the technical field of ink printing, and the printing ink is prepared from the following components: 35-45 parts of polyester modified acrylic resin, 3-10 parts of conductive particles, 4-8 parts of a dispersant, 6-9 parts of an inorganic filler, 10-20 parts of a solvent, 5-10 parts of a latent isocyanate curing agent and 0.5-1 part of an auxiliary agent. The resin structure of the selected polyester modified acrylic resin combines the advantages of saturated polyester resin and hydroxy acrylic resin, and the polyester modified acrylic resin has excellent adhesive force on PET, high resin structure stability, moderate resin hardness and no softness, and has both hardness and flexibility. The manufactured resistive pressure sensor has the advantages of being large in measuring range, stable in structure, large in static resistance, fast in elastic recovery and low in resistance hysteresis. The resin is dissolved and matched with a proper dispersing agent, conductive particles easy to disperse and inorganic filler, so that the pressure-sensitive ink has excellent stability in an ink state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ink printing, in particular to a printing ink for a thin film pressure sensor and a preparation method thereof. BACKGROUND

[0002] The resistive thin film pressure sensor is also called a thin film pressure sensor or a flexible thin film sensor. It is mainly applied in the fields of auxiliary medical treatment, auxiliary rehabilitation treatment, mechanical hand, electronic skin and health care. The pressure-sensitive material used in the existing thin film pressure sensor is generally composed of resin connecting material, conductive particles (silver, carbon black, carbon nanotube, ITO, ATO and graphite), dispersant, solvent, filler and additive. The resin connecting material mainly includes saturated polyester resin, unsaturated polyester resin, epoxy resin, acrylic resin, polyurethane resin, phenolic resin and alkyd resin. The filler includes barium sulfate, calcium carbonate, aluminum oxide, silicon dioxide, talc powder and mica sheet. The additive generally includes leveling agent, defoaming agent, coupling agent and adhesion promoter.

[0003] The existing system mixes the raw materials in a specific proportion, and then uniformly disperses them by stirring, ball milling, three-roll grinding and sand milling, so that the entire ink system becomes a stable and uniform fluid state. The ink is applied to the thin film pressure sensor by screen printing, which uniformly coats the sensor thin film electrode with the ink. The sensor is composed of two polyester fiber films. The inside of the film is printed with a conductive electrode. The electrodes on the two films are cross-shaped. The sensor ink is printed on the electrodes of the two films. When the two films are attached, a semiconductor layer with a certain resistance value is formed between the upper and lower electrodes. The semiconductor layer is formed by pressure-sensitive material. The resistance gradually decreases according to a certain rule as the pressure increases. Thus, a resistive thin film pressure sensor is formed.

[0004] However, existing resin binders have the following drawbacks: saturated polyester resins, unsaturated polyester resins, polyurethane resins, and alkyd resins, due to their inherent structural characteristics, while exhibiting excellent adhesion to PET materials, also have significant drawbacks. Because these resins have low hardness and excessive softness after curing, sensing inks made with them have low measurement range, low static resistance, may stick together above 50°C, and exhibit poor resistance stability. While using isocyanate curing agents to react with the hydroxyl groups in saturated polyester, unsaturated polyester, polyurethane, and alkyd resins can increase the Tg point and crosslinking density after film formation, it still cannot significantly improve the hardness of the ink layer. Furthermore, isocyanate itself cannot be dried by baking; therefore, excessive addition will cause the ink layer to become even softer, resulting in a low or even no measurement range for the sensing ink. To address these issues, we propose a printing ink for thin-film pressure sensors and its preparation method. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this invention provides printing ink for thin-film pressure sensors and its preparation method, thus solving the aforementioned problems.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: the printing ink for thin-film pressure sensors is prepared from the following proportions: 35-45 parts of polyester modified acrylic resin, 3-10 parts of conductive particles, 4-8 parts of dispersant, 6-9 parts of inorganic filler, 10-20 parts of solvent, 5-10 parts of latent isocyanate curing agent, and 0.5-1 parts of additives.

[0007] Preferably, the polyester-modified acrylic resin is one or more of Dexin JIXIN®LR-6363, KDD Keding MR7361 and Lihua LF-422260CD, the total solid content of the polyester-modified acrylic resin is 45-55%, the hydroxyl value ranges from 30-50 mgKOH / g, and the glass transition temperature is above 60℃.

[0008] Preferably, the dispersant is one or more of the following: UK Eucalyptus 605S, BYK-163, Efka-4310, Lubrizol 32500; the conductive particles are one or more of the following: Temico 250G, 350G, Japanese EC-300J, conductive ATO powder, and carbon fiber powder.

[0009] Preferably, the inorganic filler is one or more of nano-calcium carbonate, nano-barium sulfate, nano-alumina, fumed silica, and nano-polytetrafluoroethylene wax powder.

[0010] Preferably, the solvent is one or more of isoflurane, ethylene glycol butyl ether acetate, DBE, and PMA, and the latent isocyanate curing agent is one or more of Asahi Kasei MF-K60X, Changzhou Enke E-1070, Jingxin Huiming MDF-50, and Bayer 3175.

[0011] Preferably, the additive is one or more of organotin drying agents, organoamine drying agents, organobismuth drying agents, organosilicone leveling agents, and organosilicone defoamers.

[0012] The preparation method of printing ink for thin-film pressure sensors includes the following steps:

[0013] S1. Materials preparation: including 35-45 parts of polyester modified acrylic resin, 3-10 parts of conductive particles, 4-8 parts of dispersant, 6-9 parts of inorganic filler, 10-20 parts of solvent, 5-10 parts of latent isocyanate curing agent and 0.5-1 parts of additives;

[0014] S2. Add the polyester-modified acrylic resin, solvent, and dispersant together in the specified proportions, and disperse at 800 rpm for 10 minutes.

[0015] S3. Add the proportion of latent isocyanate curing agent and additives in step S2, disperse at 800 rpm for 5 minutes, and let stand at room temperature for 48 hours to allow the free -NCO groups in the latent isocyanate curing agent to react with the hydroxyl groups in the polyester modified acrylic resin.

[0016] After steps S4 and S3 are completed, add the proportion of conductive particles and inorganic fillers, and disperse at 800 rpm for 10 minutes.

[0017] S5. Add the appropriate proportion of silicone leveling agent and silicone defoamer to step S4, and disperse at 800 rpm for 5 minutes.

[0018] S6. After adding a certain amount of solvent to the semi-finished product obtained in step S5 to adjust the viscosity, disperse it at 800 rpm for 5 minutes, and then grind and disperse it with a three-roll mill disperser until the ink fineness is less than 2 μm to be considered qualified.

[0019] After steps S7 and S6 are completed, the ink on the three-roll mill disperser is collected into a tank, a certain amount of solvent is added to adjust the viscosity, and then filtered through a 300-mesh filter to obtain the finished product.

[0020] Preferably, in step S2, the ratio of polyester-modified acrylic resin, solvent, and dispersant is 39:6:15; in step S3, the ratio of latent isocyanate curing agent and additive added is: polyester-modified acrylic resin, solvent, dispersant, and latent isocyanate, which is 39:6:15:7.8; in step S3, the reaction process does not require intervention, and the reaction of free -NCO groups is allowed to complete naturally.

[0021] Preferably, the conductive particles and inorganic fillers added in step S4 are in the following proportions: polyester modified acrylic resin, conductive particles and inorganic fillers in a ratio of 39:8:8.5; in step S5, the silicone leveling agent and silicone defoamer are added at 0.6% and 1% of the total amount in step S3, respectively; in step S6, the solvent is added at 10% of the total amount in step S4; in step S6, the three grinding and dispersing rollers in the three-roll milling process are fixed rotating circular rollers; after grinding four times, when the fineness is tested with a scraper fineness meter and is 2.5-3μm, the number of grinding cycles is increased by one more cycle until the fineness is less than 2μm and then grinding is stopped; in step S7, the solvent is replenished to the weight before grinding in step S6.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The polyester-modified acrylic resin selected in this invention combines the advantages of saturated polyester resin and hydroxyl acrylic resin in its resin structure. This is mainly manifested in its excellent adhesion to PET, high resin structural stability, and moderate resin hardness (neither too soft nor too hard), balancing hardness and flexibility. This results in a resistive pressure sensor with a large measuring range, stable structure, high static resistance, fast elastic recovery, and low resistance hysteresis. The resin dissolution, combined with a suitable dispersant and easily dispersible conductive particles and inorganic fillers, ensures excellent stability of the pressure-sensitive ink in its ink state, preventing significant resistance deviations in the same batch of ink at different printing stages, thus demonstrating good ink stability. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation steps of the present invention;

[0025] Figure 2 This is a diagram of the PET film roll of the present invention;

[0026] Figure 3 This is a diagram of the PET film sheet of the present invention;

[0027] Figure 4 This is a diagram showing the state of the pressure-sensitive ink printed on the electrode according to the present invention;

[0028] Figure 5 This is a diagram showing the state of the product after ink printing and packaging. Detailed Implementation

[0029] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0030] Reference Figure 1 As shown, the printing ink for thin-film pressure sensors is prepared from the following proportions: 35-45 parts polyester modified acrylic resin, 3-10 parts conductive particles, 4-8 parts dispersant, 6-9 parts inorganic filler, 10-20 parts solvent, 5-10 parts latent isocyanate curing agent, and 0.5-1 parts additives.

[0031] The polyester-modified acrylic resin used is one or more of the following: Dexin JIXIN®LR-6363, KDD Keding MR7361, and Lihua LF-422260CD. Its overall solid content is generally 45-55%, hydroxyl value ranges from 30-50 mgKOH / g, and glass transition temperature is above 60℃. Polyester resins with a molecular weight above 16000 generally have excellent flexibility. When used alone as a resin binder for pressure-sensitive inks in flexible thin-film pressure sensors, the adhesion and deformation rate usually meet the requirements. However, there are issues such as rapid force saturation, slow deformation recovery, low resistance repeatability, and unstable resistance when the sensor is placed at room temperature. When acrylic resin or hydroxyl acrylic resin is used as a resin binder... While sufficient hardness allows for slow saturation under stress, high resistance repeatability, and rapid deformation recovery, a fatal flaw is that acrylic resins, due to their inherent resin structure, are generally prone to brittleness and poor adhesion on PET materials. Therefore, it is difficult to achieve a perfect resistive thin-film pressure sensor using only one of these two resins. Thus, by modifying and combining the advantages of polyester and acrylic resins, a series of problems caused by the deformation and structural stability of the resin binder can be solved more perfectly. At the same time, hydroxyl-containing polyester-modified acrylic resins can increase the adhesion of the resin to PET materials, the crosslinking density after resin curing, and the structural stability through reaction with isocyanate curing agents.

[0032] The dispersant used is one or more of the following: Eucalyptus 605S, BYK-163, Efka-4310, and Lubrizol 32500. It is used in carbon black fillers and inorganic pigments that are difficult to stabilize. It has broad compatibility, effectively prevents flocculation, floating color, and blooming, and helps to improve the storage stability of ink. In this invention, its function is to disperse conductive particles, so that the conductive particles can be uniformly and stably dispersed in the resin solution, and can effectively prevent the conductive particles from agglomerating in the resin solution.

[0033] The conductive particles used are one or more of the following: TMIK 250G, 350G, Japanese EC-300J, conductive ATO powder, and carbon fiber powder. All the conductive particles used are powders with good conductivity and easy dispersibility. In the resin solution, through chemical dispersion with a dispersant and certain physical processing dispersion technology, a stable and uniform dispersion can be formed. The dispersion formed in this invention has the characteristics of stability, good flowability, and good screen printing properties. The uniform dispersion of conductive particles makes the pressure-sensitive ink have excellent storage stability.

[0034] The inorganic fillers used are one or more of nano-calcium carbonate, nano-barium sulfate, nano-alumina, fumed silica, and nano-polytetrafluoroethylene wax powder. The main functions of the inorganic fillers are to enhance the hardness of the resin, help improve the dispersibility of conductive particles in the resin solution, and improve the surface hardness of the pressure-sensitive ink after curing. Inorganic fillers generally have the characteristics of low oil absorption value, easy dispersion, and stable physicochemical properties.

[0035] The main solvent used is one or more of isoflurane, ethylene glycol butyl ether acetate, DBE, and PMA. Its main function is to dissolve the resin and adjust the ink viscosity and drying speed. When mixed in a certain proportion, the ink can achieve better printing results in the screen printing process, including surface smoothness and ink leveling. In addition, high-boiling-point solvents are not only suitable for screen printing, but also have a certain positive effect on VOC emissions.

[0036] The latent curing agents used are one or more of Asahi Kasei MF-K60X, Changzhou Enke E-1070, Jingxin Huiming MDF-50, and Bayer 3175. Latent isocyanate curing agents refer to the end-capping of the -NCO groups in the isocyanate that can react with hydroxyl groups, so that they cannot react with hydroxyl groups at room temperature. When a certain temperature of 90-120℃ is reached, the end-capped isocyanate will be decapped and then react with the hydroxyl groups in the resin to cure and form a stable cross-linked network structure.

[0037] The additives used are one or more of organotin driers, organoamine driers, organobismuth driers, organosilicone leveling agents, and organosilicone defoamers. The organotin driers, organoamine driers, and organobismuth driers accelerate the reaction between the hydroxyl groups in the resin binder and the NCO groups in the unsealed isocyanate curing agent, thereby improving the ink curing efficiency. The organosilicone leveling agent improves the leveling properties of the ink surface after screen printing. The organosilicone defoamer eliminates bubbles generated during the ink production process and screen printing process, thereby ensuring the density of the ink film after formation.

[0038] Example 1

[0039] The preparation method of printing ink for thin-film pressure sensors includes the following steps:

[0040] S1. Materials to be prepared: including 35 parts polyester modified acrylic resin, 3 parts conductive particles, 4 parts dispersant, 6 parts inorganic filler, 10 parts solvent, 5 parts latent isocyanate curing agent and 0.5 parts additives;

[0041] S2. Add the polyester-modified acrylic resin, solvent, and dispersant together in the specified proportions, and disperse at 800 rpm for 10 minutes.

[0042] S3. Add the proportion of latent isocyanate curing agent and additives in step S2, disperse at 800 rpm for 5 minutes, and let stand at room temperature for 48 hours to allow the free -NCO groups in the latent isocyanate curing agent to react with the hydroxyl groups in the polyester modified acrylic resin.

[0043] After steps S4 and S3 are completed, add the proportion of conductive particles and inorganic fillers, and disperse at 800 rpm for 10 minutes.

[0044] S5. Add the appropriate proportion of silicone leveling agent and silicone defoamer to step S4, and disperse at 800 rpm for 5 minutes.

[0045] S6. After adding a certain amount of solvent to the semi-finished product obtained in step S5 to adjust the viscosity, disperse it at 800 rpm for 5 minutes, and then grind and disperse it with a three-roll mill disperser until the ink fineness is less than 2 μm to be considered qualified.

[0046] After steps S7 and S6 are completed, the ink on the three-roll mill disperser is collected into a tank, a certain amount of solvent is added to adjust the viscosity, and then filtered through a 300-mesh filter to obtain the finished product.

[0047] Example 2

[0048] The preparation method of printing ink for thin-film pressure sensors includes the following steps:

[0049] S1. Materials preparation: including 45 parts of polyester modified acrylic resin, 10 parts of conductive particles, 8 parts of dispersant, 9 parts of inorganic filler, 20 parts of solvent, 5 parts of latent isocyanate curing agent and 0.6 parts of additives;

[0050] S2. Add the polyester-modified acrylic resin, solvent, and dispersant together in the specified proportions, and disperse at 800 rpm for 10 minutes.

[0051] S3. Add the proportion of latent isocyanate curing agent and additives in step S2, disperse at 800 rpm for 5 minutes, and let stand at room temperature for 48 hours to allow the free -NCO groups in the latent isocyanate curing agent to react with the hydroxyl groups in the polyester modified acrylic resin.

[0052] After steps S4 and S3 are completed, add the proportion of conductive particles and inorganic fillers, and disperse at 800 rpm for 10 minutes.

[0053] S5. Add the appropriate proportion of silicone leveling agent and silicone defoamer to step S4, and disperse at 800 rpm for 5 minutes.

[0054] S6. After adding a certain amount of solvent to the semi-finished product obtained in step S5 to adjust the viscosity, disperse it at 800 rpm for 5 minutes, and then grind and disperse it with a three-roll mill disperser until the ink fineness is less than 2 μm to be considered qualified.

[0055] After steps S7 and S6 are completed, the ink on the three-roll mill disperser is collected into a tank, a certain amount of solvent is added to adjust the viscosity, and then filtered through a 300-mesh filter to obtain the finished product.

[0056] Example 3

[0057] The preparation method of printing ink for thin-film pressure sensors includes the following steps:

[0058] S1. Materials preparation: including 40 parts polyester modified acrylic resin, 9 parts conductive particles, 7 parts dispersant, 6 parts inorganic filler, 15 parts solvent, 9 parts latent isocyanate curing agent and 0.5-1 parts additives;

[0059] S2. Add the polyester-modified acrylic resin, solvent, and dispersant together in the specified proportions, and disperse at 800 rpm for 10 minutes.

[0060] S3. Add the proportion of latent isocyanate curing agent and additives in step S2, disperse at 800 rpm for 5 minutes, and let stand at room temperature for 48 hours to allow the free -NCO groups in the latent isocyanate curing agent to react with the hydroxyl groups in the polyester modified acrylic resin.

[0061] After steps S4 and S3 are completed, add the proportion of conductive particles and inorganic fillers, and disperse at 800 rpm for 10 minutes.

[0062] S5. Add the appropriate proportion of silicone leveling agent and silicone defoamer to step S4, and disperse at 800 rpm for 5 minutes.

[0063] S6. After adding a certain amount of solvent to the semi-finished product obtained in step S5 to adjust the viscosity, disperse it at 800 rpm for 5 minutes, and then grind and disperse it with a three-roll mill disperser until the ink fineness is less than 2 μm to be considered qualified.

[0064] After steps S7 and S6 are completed, the ink on the three-roll mill disperser is collected into a tank, a certain amount of solvent is added to adjust the viscosity, and then filtered through a 300-mesh filter to obtain the finished product.

[0065] Comparative Example 1

[0066] The existing method for preparing printing inks includes the following steps:

[0067] A1. According to the requirements, the pigment is dried, crushed and surface modified to improve its compatibility with the binder. Organic pigments often need to be dehydrated by squeezing and then directly mixed with the binder to form a paste ink.

[0068] A2. Use drying vegetable oil, which is refined by alkali bleaching to remove impurities, and then heated and refined to improve drying speed and film-forming performance. Synthetic resins need to be dissolved in solvent or water to form a uniform solution.

[0069] A3. Weigh the pigments, binders, and additives according to the formula ratio, with the error controlled within ±3%. The proportion of deionized water in water-based inks can reach 40%-60%, and pure water with a conductivity of less than 5μS / cm must be used.

[0070] A4. For paste-like inks, add pigments and binders to a planetary mixer and mix at a low speed of 100-300 rpm to prevent pigment powder from flying, then mix at a high speed of 800-1200 rpm to form a paste-like mixture; or directly add pigments, solvents, and resins to a ball mill or sand mill without pre-mixing.

[0071] A5. Using a three-roll mill, the shearing force is generated by the three rolls rotating at a speed ratio of 1:3:9 to refine the pigment particles to below 15μm, requiring 3-5 rolling passes; by utilizing the collision and shearing action of the grinding media, the particle size D50 ≤ 2μm is reduced.

[0072] A6. Cooling water should be introduced or the ambient temperature controlled during the grinding process. Thickeners and diluents should be added to adjust the viscosity so that the ink meets the requirements. Quality inspection and packaging should be carried out.

[0073] Application targeting differences

[0074] The example focuses on a thin-film pressure sensor, in which conductive particles are added to the raw material to meet the sensor's conductivity requirements; the comparative example uses general printing ink, which focuses on coloring and film formation, without any conductive function design.

[0075] The example uses a polyester-modified acrylic resin + latent isocyanate curing agent system, which improves ink adhesion and stability through pre-reaction, meeting the requirements of thin film sensors for lightness, thinness and weather resistance; the comparative binder system focuses more on printing film formation speed and compatibility.

[0076] The example simplifies the pretreatment process: no pigment modification or binder refining steps are required, and the materials are directly added for dispersion, making the process more efficient. The dispersion parameters in the example are uniform, and the staged material addition logic is clear, avoiding mutual interference between raw materials. In contrast, the dispersion speed of the comparative example fluctuates greatly, and some systems require multiple rounds of grinding, making process control more difficult.

[0077] The example clearly requires a thickness of <2μm, and the standard can be achieved in one three-roll milling, which is better than the 15μm upper limit of the comparative example's three-roll milling (which requires multiple millings). It is more suitable for the fineness requirements of film printing. The example reduces performance fluctuations during subsequent use by pre-reacting the curing agent and adding additives in stages. The comparative example depends on temperature control and real-time viscosity adjustment during the milling process, and its stability is more affected by the process operation.

[0078] The example is a solvent-based system, which is suitable for the insulation and moisture resistance requirements of sensors; the comparative example includes a water-based ink system, which focuses more on environmental protection, but may limit its application in electronic devices.

[0079] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A printing ink for a thin film pressure sensor, characterized by, Prepared from the following parts: polyester modified acrylic resin 35-45 parts, conductive particles 3-10 parts, dispersant 4-8 parts, inorganic filler 6-9 parts, solvent 10-20 parts, latent isocyanate curing agent 5-10 parts and auxiliary 0.5-1 parts.

2. The printed ink for thin film pressure sensors according to claim 1, characterized in that: The polyester modified acrylic resin is one or more of JIXIN LR-6363, KDD Keding MR7361 and Lifa LF-422260CD, the total solid content of the polyester modified acrylic resin is 45-55%, the hydroxyl value is 30-50 mgKOH / g, and the glass transition temperature is above 60℃.

3. The printed ink for thin film pressure sensors of claim 1, wherein: The dispersant is one or more of UKA 605S, BYK-163, Efka-4310 and Lubrizol 32500; the conductive particles are one or more of Tinci 250G, 350G, Japan EC-300J, conductive ATO powder and carbon fiber powder.

4. The printed ink for thin film pressure sensors of claim 1, wherein: The inorganic filler is one or more of nano calcium carbonate, nano barium sulfate, nano aluminum oxide, fumed silica and nano polytetrafluoroethylene wax powder.

5. The printed ink for thin film pressure sensors of claim 1, wherein: The solvent is one or more of isoflurone, ethylene glycol butyl ether acetate, DBE and PMA; the latent isocyanate curing agent is one or more of Asahi Kasei MF-K60X, Changzhou Enke E-1070, Kyoeisha Chemical MDF-50 and Bayer 3175.

6. The printed ink for thin film pressure sensors of claim 1, wherein: The auxiliary is one or more of organic tin drier, organic amine drier, organic bismuth drier, organic silicon leveling agent and organic silicon defoaming agent.

7. A method for preparing a printing ink for a thin film pressure sensor, which is applied to the printing ink for a thin film pressure sensor according to any one of claims 1 to 6, characterized by, The preparation steps are as follows: S1, preparing materials: including polyester modified acrylic resin 35-45 parts, conductive particles 3-10 parts, dispersant 4-8 parts, inorganic filler 6-9 parts, solvent 10-20 parts, latent isocyanate curing agent 5-10 parts and auxiliary 0.5-1 parts; S2, add the polyester modified acrylic resin, solvent and dispersant together in proportion, disperse at a speed of 800 rpm for 10 minutes; S3, add the proportion of latent isocyanate curing agent and auxiliary in S2 step, disperse at a speed of 800 rpm for 5 minutes, and place at room temperature for 48 hours, waiting for the free -NCO groups in the latent isocyanate curing agent to react with the hydroxyl groups in the polyester modified acrylic resin in advance; S4, after the end of S3 step, add the proportion of conductive particles and inorganic filler, and disperse at a speed of 800 rpm for 10 minutes; S5, add the proportion of organic silicon leveling agent and organic silicon defoaming agent in S4 step, disperse at a speed of 800 rpm for 5 minutes; S6, add a certain amount of solvent to adjust the viscosity of the semi-finished product obtained in S5 step, disperse at a speed of 800 rpm for 5 minutes, and grind and disperse with a three-roll grinding disperser until the ink fineness is less than 2 μm to reach the qualified state; S7, after the completion of S6 step, collect the ink on the three-roll grinding disperser into a tank, add a certain amount of solvent to adjust the viscosity, and filter with a 300 mesh screen to obtain the finished product.

8. The method of claim 7, wherein the printed ink for thin film pressure sensors is prepared by: The ratio between the polyester modified acrylic resin, solvent and dispersant in the S2 step is 39:6:15; the ratio of the latent isocyanate curing agent and the auxiliary in the S3 step is specifically: polyester modified acrylic resin, solvent, dispersant and latent isocyanate, and the ratio is: 39:6:15:7.8; the reaction process in the S3 step does not need intervention, and the free -NCO group reaction is naturally waited to be completed.

9. The method of claim 7, wherein the printed ink for thin film pressure sensors is prepared by: The ratio of the conductive particles and the inorganic filler added in the S4 step is specifically: polyester modified acrylic resin, conductive particles and inorganic filler, and the ratio is: 39:8:8.5; the silicone leveling agent and the silicone defoaming agent in the S5 step are respectively added according to 0.6% and 1% of the total amount of the S3 step; the solvent in the S6 step is 10% of the total amount in the S4 step; the three grinding and dispersing rollers in the three-roller grinding process in the S6 step are fixed rotating round rollers; after grinding for 4 times, the fineness is tested by using a doctor blade fineness meter, when the fineness is 2.5-3μm, one more grinding number is added, until the fineness is less than 2μm, and then the grinding is stopped; the solvent is supplemented to the weight before the S6 grinding in the S7 step.

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