Preparation method of gradient modulus self-adaptive damping material and application of gradient modulus self-adaptive damping material in vibration protection of precision parts

Abstract

The invention discloses a preparation method of a gradient modulus self-adaptive damping material and application of the gradient modulus self-adaptive damping material in vibration protection of precision parts, and belongs to the field of damping materials. The method comprises the following steps: preparing a hard bottom layer viscoelastic material and a slightly soft middle layer viscoelastic material: uniformly mixing urethane acrylate, pentaerythritol tetrakis (3-mercaptopropionic acid) ester and tripropylene glycol diacrylate, adding triethylamine, and slowly stirring; the dosage of the curing agent in the middle layer is reduced by 25 wt.% relative to Preparation of a top layer soft viscoelastic material: uniformly mixing urethane acrylate, pentaerythritol tetrakis (3-mercaptopropionate) and hydroxyethyl acrylate, adding triethylamine, and slowly stirring; pouring a hard viscoelastic material on the bottom layer to realize semi-curing, pouring a slightly soft viscoelastic material on the middle layer to realize semi-curing, pouring a soft viscoelastic material on the top layer to realize complete curing. Through a gradient modulus-interface strengthening-dynamic response three-dimensional cooperation mechanism, the bottleneck of rigid-flexible mismatch and energy dissipation efficiency of an existing material in microstructure protection is broken through.

Description

Technical Field

[0001] The present invention belongs to the field of damping materials, and particularly relates to a preparation method of a gradient modulus adaptive damping material and its application in vibration protection of precision components. Background Art

[0002] With the rapid development of precision electronics, aerospace, and biomedical equipment, higher requirements are put forward for the performance of materials in vibration and shock protection. According to statistics, the annual global loss due to microstructure failure caused by vibration exceeds 100 billion US dollars. Especially in precision devices such as semiconductor chips and optical components, surface micro-features (such as pads, probes) are extremely sensitive to vibration: micron-level vibration can cause signal distortion or crack propagation, while the homogenized design of traditional damping materials has fundamental defects - it is prone to resonance under high-frequency impact and damping saturation under low-frequency vibration, making it difficult to balance the contradictory requirements of stiffness and flexibility.

[0003] Although the existing gradient modulus damping materials alleviate this contradiction through the design of modulus gradient, the gradient modulus damping materials mainly construct the modulus gradient structure from the surface to the substrate through multi-phase composite processes (such as hot pressing, coprecipitation method), attempting to solve the problem of the rigidity-flexibility contradiction of traditional homogeneous materials. For example, researchers often use the hot pressing process to disperse high elastic modulus particles (such as rubber particles) in a polymer matrix and achieve modulus gradient by adjusting the particle concentration.

[0004] Although such methods can reduce the vibration transmission rate to a certain extent (30%-50% higher than homogeneous materials), there are still fundamental defects. First, it is difficult for traditional multi-phase composite processes to achieve a continuous gradient distribution of modulus. The off-line curing method results in weak interfacial bonding force between layers, which is prone to interfacial peeling or stress concentration under dynamic loads, seriously affecting the overall performance of the material. Second, the existing gradient materials lack an adaptive response mechanism to the impact load frequency. Under high-frequency impact, the high modulus layer is prone to local resonance, while under low-frequency vibration, it cannot effectively dissipate energy due to damping saturation. Third, the synergistic optimization of surface micro-structure protection and material rigidity-flexibility design is insufficient. When an impact acts on the surface features of a device (such as pads, probes), the traditional buffer layer may cause deformation of the substrate due to excessive deformation, and even cause micro-crack propagation. The root cause of these problems is that the existing materials cannot take into account the precise control of gradient modulus, dynamic load response, and interfacial performance optimization. Summary of the Invention

[0005] In view of the problems that existing gradient modulus damping materials cannot balance the precise regulation of gradient modulus, dynamic load response and interface performance optimization, etc., the present invention provides a preparation method of a gradient modulus adaptive damping material and its application in vibration protection of precision components. The present invention innovatively breaks through the above bottleneck through an in-situ gradient construction technology by means of a layered curing process: firstly, a medium modulus transition layer is introduced during the semi-curing stage of the high modulus base layer, and strong chemical bonding interfaces are formed by molecular chain diffusion, significantly improving the interlayer bonding strength; secondly, by precisely controlling the curing window, the modulus from the surface to the base can be continuously adjusted, enabling controllable attenuation of stress waves in the gradient structure; finally, a frequency-sensitive response characteristic is imparted to the material through a staged curing process - the whole domain deforms and dissipates energy in the low frequency band, and the high modulus base is used to suppress resonance in the high frequency band. The problems of interface defects, frequency insensitivity and microstructure protection failure of traditional gradient materials are solved.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] A preparation method of a gradient modulus adaptive damping material, the method being:

[0008] Step 1: Preparation of the bottom hard viscoelastic material: Mix polyurethane acrylate, pentaerythritol tetra(3-mercaptopropionate) and dipropylene glycol diacrylate evenly, remove air bubbles, add the catalyst triethylamine, and stir slowly for later use;

[0009] Step 2: Preparation of the intermediate slightly soft viscoelastic material: Mix polyurethane acrylate, pentaerythritol tetra(3-mercaptopropionate) and dipropylene glycol diacrylate evenly, remove air bubbles, add the catalyst triethylamine, and stir slowly for later use; the amount of pentaerythritol tetra(3-mercaptopropionate) in Step 2 is reduced by 25 wt.% compared with Step 1;

[0010] Step 3: Preparation of the top soft viscoelastic material: Mix polyurethane acrylate, pentaerythritol tetra(3-mercaptopropionate) and 2-hydroxyethyl acrylate evenly, remove air bubbles, add the catalyst triethylamine, and stir slowly for later use;

[0011] Step 4: Preparation of the in-situ gradient damping material: First pour the bottom hard viscoelastic material prepared in Step 1 into a mold to achieve semi-curing of the bottom layer, then pour the intermediate slightly soft viscoelastic material on this basis to achieve semi-curing of the intermediate layer. While the intermediate layer is semi-curing, at this time the bottom layer will gradually change from semi-curing to complete curing. On this basis, pour the top soft viscoelastic material to make the three-layer material completely cured to achieve the entanglement curing of the molecular chain level into a uniform whole.

[0012] Further, the specific steps of Step 1 are as follows: Polyurethane acrylate, pentaerythritol tetra(3-mercaptopropionate), and dipropylene glycol diacrylate are stirred at room temperature for 20 minutes, then placed in a vacuum oven to fully remove air bubbles. Triethylamine, as a catalyst, is slowly added to the mixed resin. Since triethylamine has extremely strong volatility and is very likely to volatilize in the vacuum oven, the system cannot be cured. To avoid the generation of air bubbles, only gentle and slow stirring of the resin can be carried out after the catalyst is dropped.

[0013] Further, in Step 1, 7 g of polyurethane acrylate (CN996), 2.7 g to 3.6 g of pentaerythritol tetra(3-mercaptopropionate) (PETMP), 3 g of dipropylene glycol diacrylate (TPGDA), and 0.1 g of triethylamine (TEA) are used. Among them, polyurethane acrylate is the resin matrix, dipropylene glycol diacrylate is an active diluent that plays a role in reducing viscosity and adjusting the network, pentaerythritol tetra(3-mercaptopropionate) is a curing agent that mainly controls the crosslinking degree of the polymer, and triethylamine is a catalyst.

[0014] Further, in Step 2, polyurethane acrylate, dipropylene glycol diacrylate, and pentaerythritol tetra(3-mercaptopropionate) (with a 25 wt.% reduction) are stirred at room temperature for 20 minutes. With less pentaerythritol tetra(3-mercaptopropionate), the crosslinking degree of the polymer network will decrease, the modulus of the material will decrease, and the flexibility will increase. Then it is placed in a vacuum oven to fully remove air bubbles. Triethylamine, as a catalyst, is slowly added to the mixed resin. Since triethylamine has extremely strong volatility and is very likely to volatilize in the vacuum oven, the system cannot be cured. To avoid the generation of air bubbles, only gentle and slow stirring of the resin can be carried out after the catalyst is dropped.

[0015] Further, in Step 2, 7 g of polyurethane acrylate (CN996), 3 g of dipropylene glycol diacrylate (TPGDA), and 0.1 g of triethylamine (TEA) are used. Among them, polyurethane acrylate is the resin matrix, dipropylene glycol diacrylate is an active diluent that plays a role in reducing viscosity and adjusting the network, pentaerythritol tetra(3-mercaptopropionate) is a curing agent that mainly controls the crosslinking degree of the polymer, and triethylamine is a catalyst.

[0016] Further, in Step 3, polyurethane acrylate, pentaerythritol tetra(3-mercaptopropionate), and 2-hydroxyethyl acrylate are stirred at room temperature for 20 minutes, then placed in a vacuum oven to fully remove air bubbles. Then triethylamine, as a catalyst, is slowly added to the mixed resin. Since triethylamine has extremely strong volatility and is very likely to volatilize in the vacuum oven, the system cannot be cured. To avoid the generation of air bubbles, only gentle and slow stirring of the resin can be carried out after the catalyst is dropped.

[0017] Further, in step three, 8.5 g of polyurethane acrylate (CN996), 3.2 - 3.6 g of pentaerythritol tetra(3-mercaptopropionate) (PETMP), 1.5 g of hydroxyethyl acrylate (HEA), and 0.1 g of triethylamine (TEA). Among them, the polyurethane acrylate is the resin matrix, the hydroxyethyl acrylate is an active diluent that plays a role in reducing viscosity and regulating the network, and is much softer than the material prepared from dipropylene glycol diacrylate. Pentaerythritol tetra(3-mercaptopropionate) is a curing agent that mainly regulates the crosslinking degree of the polymer. Triethylamine is a catalyst.

[0018] Further, in step four, the preparation of the in-situ gradient damping material: First, pour the bottom rigid viscoelastic material of step one into the mold, and let it stand at room temperature for 25 min to achieve a semi-cured state. Then, pour the middle slightly softer viscoelastic material on this basis, and let it stand at room temperature for another 25 min for semi-curing. While the middle layer is semi-curing, at this time, the bottom layer will gradually change from semi-cured to fully cured. On this basis, pour the upper soft viscoelastic material, and then let it stand at room temperature for 4 h to make the three-layer material fully cured to achieve the entanglement curing of the molecular chain level into a uniform whole.

[0019] The gradient modulus adaptive damping material prepared by the above preparation method is used for the protection of precision component vibration.

[0020] The beneficial effects of the present invention compared with the prior art are as follows:

[0021] 1. The adaptive damping material of the present invention, through the gradient modulus hierarchical design and in-situ curing process, for the protection objects with surface protrusions (such as microstructures such as chip pads, sensor probes, etc.), realizes the following core advantages: (1) The ultra-low modulus area on the surface layer absorbs impact energy through adaptive deformation, reduces the stress peak value at the tip of the protrusion, and avoids plastic deformation or fracture of the microstructure caused by local stress concentration; (2) The high modulus area at the bottom layer provides rigid support to prevent the overall deformation caused by the impact load transmitted to the substrate, and ensures the geometric stability of the protrusion array; The intermediate transition layer disperses the energy transmission path through the stress wave refraction mechanism, and eliminates the stress singularity that is prone to appear at the root of the protrusion in traditional homogeneous materials.

[0022] 2. Process innovation and performance coordination: Realize a continuous gradient of modulus (from the surface to the substrate), and form a strong chemical bonding interface between layers through molecular chain diffusion, avoiding the interface peeling problem that is prone to occur in traditional multiphase materials;

[0023] 3. Experimental verification and scenario adaptability: This design can be extended to fields such as semiconductor packaging, MEMS devices, and biomedical implant devices, providing a universal solution for the protection of surface microfeatures.

[0024] In summary, through the three-dimensional collaborative mechanism of gradient modulus-interface strengthening-dynamic response, the present invention breaks through the bottleneck of the stiffness-flexibility mismatch and energy dissipation efficiency in the microstructure protection of existing materials, providing an innovative technical path for the vibration safety protection of precision devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Compression displacement load diagrams of hard and intermediate layer viscoelastic materials with different curing agent contents;

[0026] Figure 2 Compression modulus diagrams of hard and intermediate layer viscoelastic materials with different curing agent contents;

[0027] Figure 3 Compression displacement load diagrams of soft viscoelastic materials with different curing agent contents;

[0028] Figure 4 Compression modulus diagrams of soft viscoelastic materials with different curing agent contents;

[0029] Figure 5 Optical photographs of in-situ gradient damping materials;

[0030] Figure 6 Optical photographs of dyed in-situ gradient damping materials;

[0031] Figure 7 Optical photographs of in-situ gradient damping materials combined with devices to be protected;

[0032] Figure 8 Optical photographs of in-situ gradient damping materials when impacted by a 500g gravitational force;

[0033] Figure 9 Confocal microscope imaging photographs of the surface structure of the device to be protected before impact;

[0034] Figure 10 Confocal microscope imaging photographs of the surface structure of the device to be protected after impact;

[0035] Figure 11 Optical photographs and microscope imaging photographs of in-situ gradient damping materials after impact;

[0036] Figure 12 Confocal microscope imaging photographs of in-situ gradient damping materials before impact;

[0037] Figure 13 Confocal microscope imaging photographs of in-situ gradient damping materials after impact. DETAILED DESCRIPTION OF THE INVENTION

[0038] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.

[0039] Example 1:

[0040] Preparation of the bottom hard support layer and the relatively soft middle layer: After stirring 7 g of polyurethane acrylate (CN996), 2.7 g to 3.6 g of pentaerythritol tetra(3-mercaptopropionate) (PETMP), and 3 g of dipropylene glycol diacrylate (TPGDA) at room temperature for 20 minutes, place them in a vacuum oven to fully remove air bubbles. Then, slowly add 0.1 g of the catalyst triethylamine to the mixed resin, gently stir to avoid generating air bubbles, and then pour it into a compression specimen mold.

[0041] Five different compression specimens were prepared by using different contents of the curing agent pentaerythritol tetra(3-mercaptopropionate). The formulations are shown in Table 1.

[0042] Table 1

[0043]

[0044]

[0045] The compression load test was carried out on the samples, and the compression displacement load is as Figure 1 shown, and its compression modulus is calculated as Figure 2 shown. It can be seen that the prepared samples have a high modulus. Although A-5 has the highest modulus, its compression displacement is less than that of A-4, indicating that its impact resistance is poor. Considering comprehensively, the A-4 sample with a slightly lower modulus but higher compression displacement is suitable as the bottom support layer, and the A-1 sample with a lower modulus and the highest compression displacement is suitable as the middle transition layer.

[0046] Preparation of the top soft transition layer: After stirring 8.5 g of polyurethane acrylate, 1.5 g of pentaerythritol tetra(3-mercaptopropionate), and 3.2 to 3.6 g of 2-hydroxyethyl acrylate (HEA) at room temperature for 20 minutes, place them in a vacuum oven to fully remove air bubbles. Then, slowly add 0.1 g of the catalyst triethylamine to the mixed resin, gently stir to avoid generating air bubbles, and then pour it into a compression specimen mold.

[0047] Five different compression specimens were prepared by using different contents of the curing agent pentaerythritol tetra(3-mercaptopropionate). The formulations are shown in Table 2.

[0048] Table 2

[0049] Number CN996 HEA PETMP B-1 8.5 1.5 3.2 B-2 8.5 1.5 3.4 B-3 8.5 1.5 3.6

[0050] The sample was subjected to a compressive load test, and its compressive displacement load is as Figure 3 shown, and its compressive modulus is calculated as Figure 4 shown. It can be seen that the prepared sample has a very low modulus, and among them, the B-3 sample has the lowest compressive modulus and the largest compressive displacement, and can be used as the surface layer of the gradient modulus damping material.

[0051] Example 2:

[0052] Step 1: Stir 7 g of polyurethane acrylate, 3.6 g of pentaerythritol tetrakis(3-mercaptopropionate) and 3 g of dipropylene glycol diacrylate at room temperature for 20 minutes, then put them into a vacuum oven to fully remove air bubbles. Then slowly add 0.1 g of catalyst triethylamine to the mixed resin, gently stir to avoid generating air bubbles, and then pour it into a mold so that it occupies two-fifths of the mold height. After curing at room temperature for 25 min, proceed to the next step to make it in a semi-cured state.

[0053] Step 2: Stir 7 g of polyurethane acrylate, 2.7 g of pentaerythritol tetrakis(3-mercaptopropionate) and 3 g of dipropylene glycol diacrylate at room temperature for 20 minutes, then put them into a vacuum oven to fully remove air bubbles. Then slowly add 0.1 g of catalyst triethylamine to the mixed resin, gently stir to avoid generating air bubbles, and then pour it into a mold so that its volume occupies one-fifth of the total volume of the mold. After curing for 25 min, proceed to the next step to make it in a semi-cured state.

[0054] Step 3: Stir 8.5 g of polyurethane acrylate, 1.5 g of pentaerythritol tetrakis(3-mercaptopropionate) and 3.6 g of 2-hydroxyethyl acrylate at room temperature for 20 minutes, then put them into a vacuum oven to fully remove air bubbles. Then slowly add 0.1 g of catalyst triethylamine to the mixed resin, gently stir to avoid generating air bubbles, and then pour it into a mold to fill the whole mold.

[0055] Step 4: Let it stand for 4 h to fully cure the resin in the whole mold, and the molecular chains between the three layers diffuse sufficiently and finally cure into a whole. The finally prepared viscoelastic damping material is as Figure 5 shown.

[0056] The surface of the viscoelastic damping material prepared in Example 2 was dyed and marked with a dye, as Figure 6 shown. Then take a sample with tiny protrusions on the surface to simulate the device to be protected with a characteristic structure.

[0057] Place the side with the special structure facing down on the viscoelastic damping material, as Figure 7 shown. Then apply a pressure of 500 g on its upper part to simulate the influence of a device with a complex structure under impact and vibration, as Figure 8As shown. Then the pressure is removed, and the surface of the viscoelastic damping material at the end of the impact is as Figure 9 shown. It can be seen that when impacted, the complex surface structure of the device to be protected is completely embedded in the adaptive viscoelastic damping material, giving full play to the flexible deformation characteristics of the surface adaptive layer and avoiding plastic deformation or fracture of the microstructure caused by local stress concentration.

[0058] Laser confocal testing was carried out on the surface protrusion structure of the simulated protected sample before and after impact, as Figure 9 and Figure 10 shown. It can be seen that after the impact test, the surface structure of the sample to be protected has not changed, and the height before and after remains the same. The adaptive viscoelastic damping material plays a very good role in adaptive deformation protection and will not cause plastic deformation and various damages to the surface of the protected sample.

[0059] Laser confocal testing was carried out on the whole simulated protected sample after impact, as Figure 11 shown. It can be seen that after the impact test, the surface of the entire protected sample, including the surface of the complex protrusions and the bottom surface, is contaminated with blue fuel, indicating that the prepared viscoelastic damping material completely wraps the surface of the protected device, achieving sufficient protection.

[0060] Laser confocal testing was carried out on the viscoelastic damping material before and after impact, as Figure 12 and 13 shown. It can be seen that after the impact test, the adaptive viscoelastic material completely adapts to the complex structure of the surface of the sample to be protected, and an inlaid pattern of the structure of the protected sample appears on the surface layer.

Claims

1. A method for preparing a gradient modulus adaptive damping material, characterized in that: The method is: Step 1: Preparation of bottom hard viscoelastic material: polyurethane acrylate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and tripropylene glycol diacrylate are mixed evenly, bubbles are removed, catalyst triethylamine is added, and the mixture is stirred slowly for standby use; Step 2: Preparation of a slightly soft viscoelastic material for the middle layer: polyurethane acrylate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and tripropylene glycol diacrylate are uniformly mixed, bubbles are removed, catalyst triethylamine is added, and the mixture is slowly stirred for standby use; the amount of pentaerythritol tetrakis(3-mercaptopropionic acid) ester in step 2 is reduced by 25wt.% relative to that in step 1; Step 3: Preparation of the top layer of soft viscoelastic material: polyurethane acrylate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and hydroxyethyl acrylate are mixed evenly, bubbles are removed, catalyst triethylamine is added, and the mixture is stirred slowly for standby use; Step 4: Preparation of in-situ gradient damping material: First, pour the bottom layer of hard viscoelastic material in step 1 into the mold to achieve semi-solidification of the bottom layer, then pour the middle layer of slightly soft viscoelastic material on this basis to achieve semi-solidification of the middle layer, and then pour the top layer of soft viscoelastic material on this basis to make the three layers of material completely solidified.

2. The method for preparing a gradient modulus adaptive damping material according to claim 1, characterized in that: The step 1 is specifically as follows: after stirring polyurethane acrylate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and tripropylene glycol diacrylate at room temperature for 20 minutes, the mixture is placed in a vacuum oven to fully eliminate bubbles, triethylamine catalyst is slowly added to the mixed resin, and the resin is slowly stirred after the catalyst is dropped.

3. The method for preparing a gradient modulus adaptive damping material according to claim 1 or 2, characterized in that: In step 1, 7 g polyurethane acrylate (CN996), 2.7 g to 3.6 g pentaerythritol tetrakis(3-mercaptopropionic acid) ester (PETMP), 3 g tripropylene glycol diacrylate (TPGDA), and 0.1 g triethylamine (TEA).

4. The method for preparing a gradient modulus adaptive damping material according to claim 1, characterized in that: In step 2, polyurethane acrylate, tripropylene glycol diacrylate and pentaerythritol tetrakis(3-mercaptopropionic acid) ester (reduced by 25wt.%) are stirred at room temperature for 20 minutes, placed in a vacuum oven to fully eliminate bubbles, and the catalyst triethylamine is slowly added to the mixed resin. After the catalyst is dropped in, the resin is slowly stirred.

5. The method for preparing a gradient modulus adaptive damping material according to claim 1 or 4, characterized in that: In step 2, 7 g of polyurethane acrylate (CN996), 3 g of tripropylene glycol diacrylate (TPGDA), and 0.1 g of triethylamine (TEA) were used.

6. The method for preparing a gradient modulus adaptive damping material according to claim 1, characterized in that: In step 3, polyurethane acrylate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester and hydroxyethyl acrylate are stirred at room temperature for 20 minutes, placed in a vacuum oven to fully eliminate bubbles, and then the catalyst triethylamine is slowly added to the mixed resin. After the catalyst is dropped, the resin is slowly stirred.

7. A method for preparing a gradient modulus adaptive damping material according to claim 1 or 6, characterized in that: In step 3, 8.5 g of polyurethane acrylate (CN996), 3.2-3.6 g of pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), 1.5 g of hydroxyethyl acrylate (HEA), and 0.1 g of triethylamine (TEA).

8. The method for preparing a gradient modulus adaptive damping material according to claim 1, characterized in that: In step 4, the in-situ gradient damping material is prepared: first, the bottom layer of hard viscoelastic material in step 1 is poured into the mold, and allowed to stand at room temperature for 25 minutes to achieve a semi-cured state. Then, a middle layer of slightly soft viscoelastic material is poured on this basis, and semi-cured by standing at room temperature for 25 minutes again. Then, an upper layer of soft viscoelastic material is poured on this basis, and then allowed to stand at room temperature for 4 hours to allow the three layers of material to be completely cured to achieve the entanglement and solidification of the molecular chain level into a uniform whole.

9. The gradient modulus adaptive damping material prepared by the preparation method according to any one of claims 1 to 8 is used for protecting precision parts from vibration.

Images