Photocuring 3D printing organic silicon elastomer with porous grid structure and preparation method of photocuring 3D printing organic silicon elastomer

Abstract

The invention relates to a photocuring 3D printing porous grid structure organosilicon elastomer and a preparation method thereof, and a photosensitive resin material for printing the porous grid structure organosilicon elastomer comprises the following components in parts by mass: 100 parts of vinyl silicone oil, 10-30 parts of branched structure mercapto silicone oil, 3-10 parts of a micromolecule mercapto cross-linking agent and 3-10 parts of a micromolecule vinyl cross-linking agent, 1-5 parts of a free radical photoinitiator and 3-10 parts of a reinforcing filler. The invention further provides a porous grid structure design method and a porous grid structure organic silicon elastomer preparation method. A photosensitive resin material is subjected to digital light treatment, photo-curing and 3D printing to obtain the porous grid structure organic silicon elastomer. The photo-curing 3D printing porous grid structure organic silicon elastomer provided by the invention has excellent buffering and damping effects, and can be used for aerospace equipment damping shock absorbers.

Description

Technical Field

[0001] The invention relates to a photocurable 3D printing porous grid structure organosilicon elastomer and a preparation method thereof, belonging to the technical field of materials and processes. Background Art

[0002] Silicone elastomers are a type of polymer material with silicon-oxygen bonds in the main chain of the molecule. Silicone elastomers have excellent weather resistance, heat resistance, and cold resistance, and exhibit good mechanical properties and damping and vibration reduction performance over a wide temperature range. Therefore, they are widely used in damping and vibration reduction devices for aerospace electronic equipment. As the vibration and impact mechanical environment experienced by aerospace equipment becomes increasingly harsh, the existing damping product structures have problems such as too small buffering stroke and unsatisfactory buffering effect due to limited compression. Therefore, there is a demand for damping and vibration reduction devices with large buffering stroke and high buffering efficiency. The porous grid structure has excellent buffering and vibration reduction performance, and the preparation of silicone elastomer vibration reduction devices with a porous grid structure has become a research hotspot in recent years. However, most traditional silicone elastomers are formed by compression molding and hot vulcanization, and it is difficult to prepare silicone elastomers with a porous grid structure.

[0003] 3D printing technology, also known as additive manufacturing technology, is a new manufacturing technology that converts three-dimensional manufacturing into two-dimensional manufacturing by accumulating raw materials layer by layer. 3D printing technology can be used to prepare porous mesh structure silicone elastomers. At present, the main methods for forming 3D printed silicone elastomers are direct writing printing and photocuring printing. Compared with direct writing printing, photocuring 3D printing has faster printing speed and higher printing accuracy. The main problem of existing photocuring 3D printed silicone elastomers is that the mechanical strength of the printed products is too low, making it difficult to print and form porous mesh structures and use them for structural parts. The Chinese invention patent "A photocuring 3D printed silicone rubber ink and its preparation method" (patent number CN115637048A) discloses a silicone rubber with a two-step photothermal curing mechanism. The silicone rubber system combines the advantages of high precision of photocuring printing and enhancement of heat-curing silicone rubber, and successfully prepares porous structure silicone rubber, but the mechanical strength of the silicone rubber obtained by the method is still low. Huang et al. used photocuring 3D printing to prepare a high-strength ultra-stretchable silicone elastomer, but its silicone photosensitive resin material has high viscosity and poor processability, and requires special printing equipment for molding [ACS applied materials & interfaces, 11, 2019].

[0004] In order to realize the manufacturing of porous mesh structure silicone elastomers and promote the development of 3D printing technology, it is necessary to develop a new type of silicone photosensitive material with low viscosity, fast photocuring speed, excellent mechanical properties of the cured product, and good 3D printing processability, and use it for the manufacturing of porous mesh structure silicone elastomers. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a photocurable 3D printed porous grid structure silicone elastomer, which solves the problem of poor mechanical properties of existing photocurable 3D printed silicone elastomers, realizes the preparation of high-strength and low-viscosity photocurable 3D printed silicone materials and the manufacture of porous grid structure silicone elastomers, and can meet the development needs of new damping and vibration reduction devices for aerospace models.

[0006] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0007] A method for preparing a photocurable 3D printed porous mesh structure silicone elastomer comprises the following steps:

[0008] (1) Preparing a photosensitive resin material for printing a porous grid structured silicone elastomer;

[0009] (2) Designing porous mesh structures of silicone elastomers;

[0010] (3) preheating the photosensitive resin material described in step (1) and performing 3D printing to obtain a model blank;

[0011] (4) cleaning and post-curing the model body obtained in step (3) to obtain the porous grid structure silicone elastomer;

[0012] The photosensitive resin material components are as follows in parts by mass: 100 parts of vinyl silicone oil, 10 to 30 parts of branched structure mercapto silicone oil, 3 to 10 parts of small molecule mercapto crosslinking agent, 3 to 10 parts of small molecule vinyl crosslinking agent, 1 to 5 parts of free radical photoinitiator, and 3 to 10 parts of reinforcing filler.

[0013] The preparation method of the photosensitive resin material in step (1) is as follows: the vinyl silicone oil, branched structure mercapto silicone oil, small molecule mercapto crosslinking agent, small molecule vinyl crosslinking agent, free radical photoinitiator and reinforcing filler are added to a stirrer in sequence, and stirred and mixed to obtain a photosensitive resin material, the stirring speed is 300-400 r / min, and the stirring time is 2-3 h.

[0014] The vinyl silicone oil is vinyl terminated polydimethylsiloxane.

[0015] The viscosity of the vinyl silicone oil is 4000-6000 mPa.s.

[0016] The branched mercapto silicone oil is a condensation product of 3-mercaptopropyltrimethoxysilane, dimethyldimethoxysilane and hexamethyldisiloxane, and its chemical structure is as follows:

[0017]

[0018] Wherein m is the number of methyl chain segments, n is the number of thiol chain segments, m = 60-80, n = 10-20;

[0019] Based on the total mass of the branched mercapto silicone oil, the mercapto content is 1.4-2.3 mmol / g, and the viscosity of the branched mercapto silicone oil is (25° C.) 300-1000 mPa.s.

[0020] The preparation method of the branched structure mercapto silicone oil is as follows: in the presence of a catalyst, hexamethyldisiloxane, dimethyldimethoxydisiloxane, 3-mercaptopropyltrimethoxysilane, deionized water and a solvent are added to a reactor to carry out a hydrolysis condensation reaction, wherein the hydrolysis reaction temperature is 40 to 50° C., and the reaction time is 20 to 24 hours; the condensation reaction is 80 to 100° C., and the reaction time is 10 to 12 hours. The mixture after the above reaction is azeotropically desorbed from the hydrolysis condensation reaction product methanol, the reaction product is washed with deionized water to a pH of 6-7, the solvent is evaporated, and finally the branched structure mercapto silicone oil is obtained.

[0021] The catalyst is concentrated hydrochloric acid, and the solvent is toluene.

[0022] The small molecule mercapto crosslinking agent is trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetrakis(3-mercaptopropionate) or a mixture of the two.

[0023] The small molecule vinyl crosslinking agent is one or a mixture of tetramethyldivinyldisiloxane or tetramethyltetravinylcyclotetrasiloxane.

[0024] The free radical photoinitiator is a mixture of photoinitiators 819 and 1173 or photoinitiator TPO-L.

[0025] The reinforcing filler is fumed silica, and the particle size is less than 50 nm.

[0026] The porous grid structure of the organic silicon elastomer is a three-periodic minimal surface structure.

[0027] The three-periodic minimal surface structure design method is as follows:

[0028] (1) Generate an ideal unit cell three-periodic minimal surface structure based on mathematical equation modeling;

[0029] (2) Finite element mechanical simulation analysis is adopted to optimize the structural parameters of the three-period minimal surface with the minimum value of the maximum acceleration response under the frequency impact condition of 50-5000HZ as the optimization target. The structural parameters of the three-period minimal surface include shape parameter C, unit cell thickness, unit cell size and unit cell deflection angle. The shape parameter C has a value range of -0.8 to 0.8, the unit cell thickness has a value range of 0.2 to 2, the unit cell size has a value range of 0.5 to 12, the unit cell deflection angle along the X direction is 0 to 60°, and the deflection angle along the Y direction is 0 to 60°. The typical solid structure model is converted into a three-period minimal surface structure model through graphic Boolean operation.

[0030] The parameters of the 3D printing method in step (3) are as follows: the preheating temperature of the photosensitive resin material is 40-50°C, the preheating time is 10-30min, the printing layer thickness is 50-200um, the exposure time is 5-15s, the exposure intensity is 10-15mW / cm2, the printing platform lifting speed is 1-5mm / min, the material trough preheating temperature is 40-50°C, and the material trough preheating time is 10-30min.

[0031] The 3D printing method is digital light processing photocuring 3D printing.

[0032] In the step (4), the cleaning method is to firstly use octamethylcyclotetrasiloxane to ultrasonically clean the printed model body for 3-5 minutes, and then use anhydrous ethanol to ultrasonically clean the printed model body for 3-5 minutes.

[0033] In the step (4), the post-curing process is: post-curing with ultraviolet light in a UV box for 20-30 minutes, and then post-curing in a 60-80° C. oven for 1-2 hours.

[0034] Compared with the prior art, the embodiments of the present invention have at least the following beneficial effects:

[0035] (1) The photosensitive resin material of the present invention adopts a basic formula of photosensitive resin material obtained by compounding vinyl silicone oil with branched structure mercapto silicone oil and free radical photoinitiator, and further adding reinforcing filler, small molecule mercapto cross-linking agent and small molecule vinyl cross-linking agent to simultaneously improve the strength of the cured product and reduce the viscosity. It has a faster photocuring rate, a smaller curing shrinkage rate, a lower viscosity and excellent mechanical properties, and can be used for photocuring 3D printing preparation of silicone rubber products with complex structures.

[0036] (2) The porous grid structure of the silicone elastomer described in the present invention is designed using finite element mechanical simulation, and preferably a three-periodic minimal surface structure is used. This structure has excellent cushioning and vibration reduction effects.

[0037] (3) The photocurable 3D printed porous grid structure silicone elastomer of the present invention has excellent buffering and vibration reduction effects and can be used in aerospace equipment damping and vibration reduction devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The three-period minimal surface structure model for the optimal design of the annular vibration damping pad;

[0039] Figure 2 A three-period minimal surface structure annular vibration damping pad made for photo-stereolithography 3D printing. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] The method for preparing the photocurable 3D printed porous mesh structure organosilicon elastomer of the present invention is as follows:

[0042] (1) Preparing a photosensitive resin material for printing a porous grid structured silicone elastomer;

[0043] (2) Designing porous mesh structures of silicone elastomers;

[0044] (3) preheating the photosensitive resin material described in step (1) and performing 3D printing to obtain a model blank;

[0045] (4) cleaning and post-curing the model body obtained in step (3) to obtain the porous grid structure silicone elastomer;

[0046] The photosensitive resin material used for printing porous grid structure silicone elastomer has the following contents by mass fraction: 100 parts of vinyl silicone oil, 10-20 parts of branched structure mercapto silicone oil, 3-10 parts of small molecule mercapto crosslinking agent, 3-10 parts of small molecule vinyl crosslinking agent, 1-5 parts of free radical photoinitiator, and 3-10 parts of reinforcing filler.

[0047] The vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 4000-6000 mPa.s. Preferably, the vinyl content of the vinyl silicone oil is 0.3-0.4 mmol / g.

[0048] The branched mercapto silicone oil is a condensation product of 3-mercaptopropyltrimethoxysilane, dimethyldimethoxysilane and hexamethyldisiloxane, and its typical chemical structure is as follows:

[0049]

[0050] Wherein m is the number of methyl chain segments, n is the number of thiol chain segments, m = 60-80, n = 10-20;

[0051] The mercapto content of the branched mercapto silicone oil is 1.4-2.3 mmol / g; the viscosity of the branched mercapto silicone oil is (25° C.) 300-1000 mPa.s; preferably, the viscosity of the branched mercapto silicone oil is 300-500 mPa.s.

[0052] The branched mercapto silicone oil is prepared by the following steps:

[0053] S1: In the presence of a catalyst, hexamethyldisiloxane, dimethyldimethoxydisiloxane, 3-mercaptopropyltrimethoxysilane, deionized water and a solvent are added to a reactor to carry out a hydrolysis condensation reaction; the catalyst is concentrated hydrochloric acid, the solvent is preferably toluene, the hydrolysis reaction temperature is 40-50°C, and the reaction time is 20-24h; the condensation reaction is 80-100°C, and the reaction time is 10-12h.

[0054] S2: removing methanol from the mixture after the above reaction by azeotropic distillation, washing the reaction product with a large amount of deionized water to make it neutral, and evaporating the solvent to finally obtain a branched structure mercapto silicone oil.

[0055] The reinforcing filler is fumed silica, and the particle size is less than 50 nm; preferably, the selected reinforcing filler is hydrophobic fumed silica; more preferably, the selected reinforcing filler is Degussa R812S.

[0056] The thiol small molecule crosslinking agent is trimethylolpropane tris(3-mercaptopropionate) ester, pentaerythritol tetrakis(3-mercaptopropionate) ester or a mixture of the two; preferably, the selected thiol small molecule crosslinking agent is trimethylolpropane tris(3-mercaptopropionate) ester.

[0057] The vinyl small molecule crosslinking agent is one of tetramethyldivinyldisiloxane and tetramethyltetravinylcyclotetrasiloxane or a mixture of the two; preferably, the selected mercapto small molecule crosslinking agent is tetramethyltetravinylcyclotetrasiloxane.

[0058] The free radical photoinitiator is a mixture of photoinitiators 819 and 1173 in a mass ratio of 1:1 or photoinitiator TPO-L; preferably, the selected photoinitiator is TPO-L.

[0059] The present invention provides a method for preparing the above-mentioned organosilicon photosensitive material, according to the following steps:

[0060] 1) Weigh vinyl-terminated silicone oil, branched mercapto silicone oil, small molecule mercapto crosslinking agent, small molecule vinyl crosslinking agent, fumed silica, and photoinitiator according to proportion;

[0061] 2) Adding the terminal vinyl silicone oil, branched structure mercapto silicone oil, small molecule mercapto crosslinking agent, small molecule vinyl crosslinking agent, fumed silica, and photoinitiator into a stirrer in sequence, stirring and mixing at a low speed to obtain a photosensitive resin; wherein the rotation speed of the low-speed stirring is 300-400 r / min, and the stirring time is 2-3 h.

[0062] The present invention provides a design method for a porous grid structure, wherein the porous grid structure is a three-periodic minimal surface structure, and preferably, the porous grid structure is a G-type three-periodic minimal surface structure. The porous grid structure of the present invention is designed according to the following steps:

[0063] 1) Generate an ideal unit cell three-periodic minimal surface structure based on mathematical equation modeling, and transform the typical solid structure model into a three-periodic minimal surface structure model through graphic Boolean operations;

[0064] 2) Finite element mechanical simulation analysis is used to optimize the structural parameters of the three-period minimal surface with the minimum value of the maximum acceleration response under high-frequency impact conditions as the optimization target. The structural parameters of the three-period minimal surface include shape parameter C, unit cell thickness, unit cell size and unit cell deflection angle. The structural design shape parameter C ranges from -0.8 to 0.8, the unit cell thickness ranges from 0.2 to 2, the unit cell size ranges from 0.5 to 12, the unit cell deflection angle along the X direction is 0 to 60°, and the deflection angle along the Y direction is 0 to 60°.

[0065] The present invention also provides a method for preparing a photocurable 3D printed porous mesh structure organosilicon elastomer. Preferably, the photocurable 3D printing method is digital light processing photocurable 3D printing.

[0066] The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer is carried out according to the following steps:

[0067] 1) Preheat the prepared organosilicon photosensitive resin material at 40-50°C for 10-30 minutes and then pour it directly into the material tank of the light-curing 3D printer;

[0068] 2) Set the print layer thickness to 50-200um, exposure time to 5-15s, and exposure intensity to 10-15mW / cm 2 The lifting speed of the printing platform is 1-5 mm / min, and the heating temperature of the material tank is 40-50°C; preferably, the printing layer thickness is set to 100 um, the exposure time is 8-10 s, and the exposure intensity is 10-12 mW / cm 2 , the lifting speed of the printing platform is 3-5mm / min, the heating temperature of the material tank is 40-50℃, and the preheating temperature of the material tank is 40-50℃.

[0069] 3) The model blank is cleaned and post-cured to obtain the porous grid structure organic silicone elastomer.

[0070] In the above-mentioned step (3), the cleaning method is to first ultrasonically clean the printed model body with octamethylcyclotetrasiloxane for 3-5 minutes, and then ultrasonically clean the printed model body with anhydrous ethanol for 3-5 minutes; the post-curing process is: post-curing with ultraviolet light in a UV box for 30 minutes, and then post-curing in a 60-80°C oven for 1-2 hours.

[0071] Example 1

[0072] A method for synthesizing branched structure mercapto silicone oil, wherein the mercapto content is designed to be 1.4 mmol / g.

[0073] 4.05g (0.025mol) hexamethyldisiloxane, 180g (1.5mol) dimethyldimethoxydisiloxane, 49g (0.25mol) 3-mercaptopropyltrimethoxysilane, 101g deionized water and 350g toluene were added to a reactor equipped with mechanical stirring, nitrogen inlet tube, thermometer and dropping funnel. 154g concentrated hydrochloric acid was added dropwise to the system, and a water bath was used to cool the reaction system to keep the temperature of the reaction system no higher than 50°C. After the hydrochloric acid was added, the mixture was stirred for 24h to ensure that the reactants were fully hydrolyzed. The temperature of the system was then raised to 100°C for condensation reaction, the reaction time was 10 to 12h, and the methanol produced in the reaction process was separated from the system by azeotropy. Finally, the product was washed with a large amount of deionized water to neutralize, and the solvent was evaporated to finally obtain a branched structure mercapto silicone oil, named SH-1.

[0074] Example 2

[0075] A method for synthesizing branched structure mercapto silicone oil, wherein the mercapto content is designed to be 1.9 mmol / g.

[0076] 4.05g (0.025mol) hexamethyldisiloxane, 240g (2mol) dimethyldimethoxydisiloxane, 98g (0.5mol) 3-mercaptopropyltrimethoxysilane, 148.5g deionized water and 350g toluene were added to a reactor equipped with mechanical stirring, nitrogen inlet tube, thermometer and dropping funnel. 154g concentrated hydrochloric acid was added dropwise to the system, and a water bath was used to cool the reaction system to keep the temperature of the reaction system no higher than 50°C. After the hydrochloric acid was added, the mixture was stirred for 24h to ensure that the reactants were fully hydrolyzed. The temperature of the system was then raised to 100°C for condensation reaction, the reaction time was 10 to 12h, and the methanol produced in the reaction process was separated from the system by azeotropy. Finally, the product was washed with a large amount of deionized water to neutralize, and the solvent was evaporated to finally obtain a branched structure mercapto silicone oil, named SH-2.

[0077] Example 3

[0078] A method for synthesizing branched structure mercapto silicone oil, wherein the mercapto content is designed to be 2.3 mmol / g.

[0079] 4.05g (0.025mol) hexamethyldisiloxane, 180g (1.5mol) dimethyldimethoxydisiloxane, 98g (0.5mol) 3-mercaptopropyltrimethoxysilane, 121.5g deionized water and 350g toluene were added to a reactor equipped with mechanical stirring, nitrogen inlet tube, thermometer and dropping funnel. 154g concentrated hydrochloric acid was added dropwise to the system, and a water bath was used to cool the reaction system to keep the temperature of the reaction system no higher than 50°C. After the hydrochloric acid was added, the mixture was stirred for 24h to ensure that the reactants were fully hydrolyzed. The temperature of the system was then raised to 100°C for condensation reaction, the reaction time was 10 to 12h, and the methanol produced in the reaction process was separated from the system by azeotropy. Finally, the product was washed with a large amount of deionized water to neutralize, and the solvent was evaporated to finally obtain a branched structure mercapto silicone oil, named SH-3.

[0080] Example 4

[0081] The preparation method of the organosilicon photosensitive resin material is as follows:

[0082] First, weigh the raw materials according to the formula ratio: the raw material components of the silicone photosensitive resin are calculated by weight as follows:

[0083]

[0084] Then, pour all the components into a stirrer and stir and mix them at a low speed to obtain a photosensitive resin; the rotation speed of the low-speed stirring is 300-400 r / min, and the stirring time is 2-3 hours.

[0085] Example 5

[0086] The preparation method of the organosilicon photosensitive resin material is as follows:

[0087] First, weigh the raw materials according to the formula ratio: the raw material components of the silicone photosensitive resin are calculated by weight as follows:

[0088]

[0089] Then, pour all the components into a stirrer and stir and mix them at a low speed to obtain a photosensitive resin; the rotation speed of the low-speed stirring is 300-400 r / min, and the stirring time is 2-3 hours.

[0090] Example 6

[0091] The preparation method of the organosilicon photosensitive resin material is as follows:

[0092] First, weigh the raw materials according to the formula ratio: the raw material components of the silicone photosensitive resin are calculated by weight as follows:

[0093]

[0094] Then, pour all the components into a stirrer and stir and mix them at a low speed to obtain a photosensitive resin; the rotation speed of the low-speed stirring is 300-400 r / min, and the stirring time is 2-3 hours.

[0095] Evaluation of mechanical properties of cured silicone photosensitive resin materials.

[0096] The mechanical properties of the cured organic silicon photosensitive resin materials of Examples 4-6 were evaluated using the GB / T2568-2008 test standard.

[0097] Table 1 Mechanical properties of cured organic silicon photosensitive resin materials of Examples 4-6

[0098]

[0099] Example 7

[0100] The porous grid structure design method is as follows:

[0101] Step 1: Generate an ideal unit body three-periodic minimal surface structure according to mathematical equation modeling, and transform the solid structure annular vibration damping pad model into a three-periodic minimal surface structure annular vibration damping pad model through graphic Boolean operation;

[0102] Step 2: Finite element mechanical simulation analysis is used to optimize the structural parameters of the three-period minimal surface structure annular vibration damping pad with the minimum value of the maximum acceleration response under high-frequency impact conditions as the optimization target; the shape parameters of the optimized three-period minimal surface structure annular vibration damping pad are 0.187, the unit cell thickness is 1.5, the unit cell size is 6, and the unit cell deflection angle is 6°.

[0103] Example 8

[0104] 3D printing of porous mesh structured silicone elastomer

[0105] Step 1: Use DLP 3D printing equipment to print the organic silicon photosensitive resin obtained in Examples 4 to 6. The printed model is the three-period minimal surface structure annular vibration damping pad obtained in Example 7. The printing parameters are set to set the printing layer thickness to 50um, the exposure time to 8s, and the exposure intensity to 10mW / cm 2 , the printing platform lifting speed is 3mm / min, and the material trough heating temperature is 50℃.

[0106] Step 2: Place the printed sample in octamethylcyclotetrasiloxane for ultrasonic treatment for 5 minutes, then place it in ethanol for ultrasonic treatment for 3 minutes, then place it in a UV box for curing for 30 minutes, and finally place it in an 80°C oven for curing for 1 hour to finally obtain a porous grid structure silicone elastomer.

[0107] Example 9

[0108] 3D printing of porous mesh structured silicone elastomer

[0109] Step 1: Use DLP 3D printing equipment to print the organic silicon photosensitive resin obtained in Examples 4 to 6. The printed model is the three-period minimal surface structure annular vibration damping pad obtained in Example 7. The printing parameters are set to set the printing layer thickness to 100um, the exposure time to 10s, and the exposure intensity to 12mW / cm 2 , the printing platform lifting speed is 3mm / min, and the material trough heating temperature is 50℃.

[0110] Step 2: Place the printed sample in octamethylcyclotetrasiloxane for ultrasonic treatment for 5 minutes, then place it in ethanol for ultrasonic treatment for 3 minutes, then place it in a UV box for curing for 30 minutes, and finally place it in an 80°C oven for curing for 1 hour to finally obtain a porous grid structure silicone elastomer.

[0111] Example 10

[0112] 3D printing of porous mesh structured silicone elastomer

[0113] Step 1: Use DLP 3D printing equipment to print the organic silicon photosensitive resin obtained in Examples 4 to 6. The printed model is the three-period minimal surface structure annular vibration damping pad obtained in Example 7. The printing parameters are set to set the printing layer thickness to 200um, the exposure time to 12s, and the exposure intensity to 15mW / cm 2 , the printing platform lifting speed is 5mm / min, and the material tank heating temperature is 50℃.

[0114] Step 2: Place the printed sample in octamethylcyclotetrasiloxane for ultrasonic treatment for 5 minutes, then place it in ethanol for ultrasonic treatment for 3 minutes, then place it in a UV box for curing for 30 minutes, and finally place it in an 80°C oven for curing for 1 hour to finally obtain a porous grid structure silicone elastomer.

[0115] Evaluation of the cushioning properties of photocurable 3D printed porous grid structure silicone elastomer.

[0116] The cushioning performance of the photocurable 3D printed porous grid structure silicone elastomer obtained in Examples 8 to 10 was evaluated by high-frequency impact test.

[0117] Table 2 Buffering properties of photocurable 3D printed porous mesh structure silicone elastomer

[0118]

[0119] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0120] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for preparing a photocurable 3D printed porous mesh structure silicone elastomer, characterized in that: The following steps are involved: (1) Preparing a photosensitive resin material for printing a porous grid structured silicone elastomer; (2) Designing porous mesh structures of silicone elastomers; (3) preheating the photosensitive resin material described in step (1) and performing 3D printing to obtain a model blank; (4) cleaning and post-curing the model body obtained in step (3) to obtain the porous grid structure silicone elastomer; The photosensitive resin material components are as follows in parts by mass: 100 parts of vinyl silicone oil, 10 to 30 parts of branched structure mercapto silicone oil, 3 to 10 parts of small molecule mercapto crosslinking agent, 3 to 10 parts of small molecule vinyl crosslinking agent, 1 to 5 parts of free radical photoinitiator, and 3 to 10 parts of reinforcing filler.

2. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The preparation method of the photosensitive resin material in step (1) is as follows: the vinyl silicone oil, branched structure mercapto silicone oil, small molecule mercapto crosslinking agent, small molecule vinyl crosslinking agent, free radical photoinitiator and reinforcing filler are added to a stirrer in sequence, and stirred and mixed to obtain a photosensitive resin material, the stirring speed is 300-400 r / min, and the stirring time is 2-3 h.

3. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The vinyl silicone oil is vinyl terminated polydimethylsiloxane.

4. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 3, characterized in that: The viscosity of the vinyl silicone oil is 4000-6000 mPa.s.

5. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The branched mercapto silicone oil is a condensation product of 3-mercaptopropyltrimethoxysilane, dimethyldimethoxysilane and hexamethyldisiloxane, and its chemical structure is as follows: Wherein m is the number of methyl chain segments, n is the number of thiol chain segments, m=60-80, n=10-20.

6. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 5, characterized in that: Based on the total mass of the branched mercapto silicone oil, the mercapto content is 1.4-2.3 mmol / g, and the viscosity of the branched mercapto silicone oil is (25° C.) 300-1000 mPa.s.

7. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 5, characterized in that: The preparation method of the branched structure mercapto silicone oil is as follows: in the presence of a catalyst, hexamethyldisiloxane, dimethyldimethoxydisiloxane, 3-mercaptopropyltrimethoxysilane, deionized water and a solvent are added to a reactor to carry out a hydrolysis condensation reaction, wherein the hydrolysis reaction temperature is 40 to 50° C., and the reaction time is 20 to 24 hours; the condensation reaction is 80 to 100° C., and the reaction time is 10 to 12 hours. The mixture after the above reaction is azeotropically desorbed from the hydrolysis condensation reaction product methanol, the reaction product is washed with deionized water to a pH of 6 to 7, the solvent is evaporated, and finally the branched structure mercapto silicone oil is obtained.

8. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 7, characterized in that: The catalyst is concentrated hydrochloric acid, and the solvent is toluene.

9. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The small molecule mercapto crosslinking agent is trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetrakis(3-mercaptopropionate) or a mixture of the two.

10. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The small molecule vinyl crosslinking agent is tetramethyldivinyldisiloxane or tetramethyltetravinylcyclotetrasiloxane, or a mixture of the two.

11. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The free radical photoinitiator is a mixture of photoinitiators 819 and 1173 or photoinitiator TPO-L.

12. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The reinforcing filler is fumed silica, and the particle size is less than 50 nm.

13. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The porous grid structure of the organic silicon elastomer is a three-periodic minimal surface structure.

14. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 13, characterized in that: The three-periodic minimal surface structure design method is as follows: (1) Generate an ideal unit cell three-periodic minimal surface structure based on mathematical equation modeling; (2) Finite element mechanical simulation analysis is adopted to optimize the structural parameters of the three-period minimal surface with the minimum value of the maximum acceleration response under the frequency impact condition of 50-5000HZ as the optimization target. The structural parameters of the three-period minimal surface include shape parameter C, unit cell thickness, unit cell size and unit cell deflection angle. The shape parameter C has a value range of -0.8 to 0.8, the unit cell thickness has a value range of 0.2 to 2, the unit cell size has a value range of 0.5 to 12, the unit cell deflection angle along the X direction is 0 to 60°, and the deflection angle along the Y direction is 0 to 60°. The typical solid structure model is converted into a three-period minimal surface structure model through graphic Boolean operation.

15. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: The parameters of the 3D printing method in step (3) are: the preheating temperature of the photosensitive resin material is 40-50°C, the preheating time is 10-30min, the printing layer thickness is 50-200um, the exposure time is 5-15s, and the exposure intensity is 10-15mW / cm 2 , the lifting speed of the printing platform is 1-5mm / min, the preheating temperature of the material tank is 40-50℃, and the preheating time of the material tank is 10-30min.

16. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 15, characterized in that: The 3D printing method is digital light processing photocuring 3D printing.

17. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: In the step (4), the cleaning method is to firstly use octamethylcyclotetrasiloxane to ultrasonically clean the printed model body for 3-5 minutes, and then use anhydrous ethanol to ultrasonically clean the printed model body for 3-5 minutes.

18. The method for preparing a photocurable 3D printed porous mesh structure silicone elastomer according to claim 1, characterized in that: In the step (4), the post-curing process is: post-curing with ultraviolet light in a UV box for 20-30 minutes, and then post-curing in a 60-80° C. oven for 1-2 hours.

19. A photocurable 3D printed porous mesh structure silicone elastomer, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 18.

Images