Damping rubber and its preparation method and application

Abstract

This invention provides a damping adhesive, its preparation method, and its application. The raw materials for preparing the damping adhesive include butadiene rubber, nitrile rubber, epoxy resin, PVC paste resin, γ-glycidoxypropyltrimethoxysilane, calcium carbonate, crosslinking agent, and curing agent. By selecting butadiene rubber and nitrile rubber in combination, and supplementing them with epoxy resin and PVC paste resin, the damping adhesive exhibits excellent bonding performance and elasticity. Further addition of γ-glycidoxypropyltrimethoxysilane promotes a synergistic effect among the components, increasing the adhesive strength of the damping adhesive without reducing its storage stability. The resulting damping adhesive possesses excellent adhesion, heat resistance, water resistance, weather resistance, and storage stability, making it suitable for bonding metal sheets.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a shock-absorbing adhesive, its preparation method, and its application. Background Technology

[0002] With the continuous improvement of people's living standards, automobiles have become an indispensable means of transportation. The comfort of driving and riding in a car has become an increasingly important focus for buyers. Vibration and noise of the car body are undoubtedly the main reasons affecting driving and riding comfort. The body of a modern car is composed of a skeleton and outer skin panels that are connected to form an aesthetically pleasing appearance and a high-strength load-bearing structure. During driving and idling, weak parts such as the outer skin panels of the body will vibrate, forming an excitation source. This vibration is transmitted to the car body and propagates in the form of vibration, which in turn causes vibration in other parts of the car body, reducing driving and riding comfort.

[0003] To prevent vibration transmission between the outer panel and the reinforcing ribs, currently, automotive outer panels and reinforcing ribs are connected using polymer materials such as damping adhesives and tapes for vibration reduction. These materials are cured through an electrophoresis process to form a highly elastic rubber that connects the skin and the reinforcing ribs together. By applying these products, vibration damping, resonance control, and damping are achieved, thereby avoiding or eliminating low-frequency vibrations in the vehicle and improving its NVH performance. Damping adhesives are single-component paste-like products with synthetic rubber as the main component. They are primarily used between the inner and outer panels of automotive doors, hoods, trunk lids, and roof beams to bond cold-rolled steel sheets. After baking and curing, they foam to enhance the connection between the inner and outer panels, thus reducing vibration and noise.

[0004] Due to the increasing demand for lightweight automobiles and the vigorous development of the new energy vehicle industry in recent years, more and more aluminum sheet materials are being used. Existing damping adhesive products are mostly for 5-series and 6-series aluminum. CN110818972A discloses a PVC-free damping adhesive, which is composed of the following components by weight percentage: 8-12% styrene-butadiene rubber, 4-6% butadiene rubber, 15-18% heavy calcium carbonate, 22-25% nano-activated calcium carbonate, 2-4% calcium oxide, 18-22% plasticizer, 1-4% zinc oxide, 0.5-1% carbon black, 4-6% epoxy resin, 0.1-0.8% AC foaming agent, 0.4-1% p-benzoquinone dioxime, 0.5-1% dicyandiamide, 2-3% maleic anhydride grafted modified polybutadiene, 0.4-1% sulfur, and 8-10% paraffin oil. The PVC-free damping adhesive obtained by this invention meets industry standards while greatly reducing VOC content, making it environmentally friendly. However, due to the significant differences between aluminum alloy and cold-rolled sheet, the damping adhesive obtained by this invention has poor adhesion to aluminum alloy sheets and poor heat resistance, which cannot meet the requirements of automobile manufacturers.

[0005] Therefore, developing a damping adhesive with high bonding performance and excellent heat resistance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a shock-absorbing adhesive, its preparation method, and its application. The shock-absorbing adhesive is formulated by selecting nitrile rubber, butadiene rubber, epoxy resin, PVC paste resin, γ-glycidyl etheroxypropyltrimethoxysilane, calcium carbonate, a crosslinking agent, and a curing agent. It exhibits high viscosity at room temperature and, after baking and foaming, becomes a rubber elastomer, possessing excellent shock absorption and sealing properties. It is suitable for use in automotive doors, engine hoods, trunk lids, roof beams, and connections between inner and outer panels.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a shock-absorbing adhesive, wherein the raw materials for preparing the shock-absorbing adhesive include nitrile rubber, cis-butadiene rubber, epoxy resin, PVC paste resin, γ-glycidoxypropyltrimethoxysilane, calcium carbonate, crosslinking agent and curing agent.

[0009] The damping adhesive provided by this invention first uses a combination of nitrile rubber and butadiene rubber, supplemented with epoxy resin and PVC paste resin, to give the damping adhesive excellent bonding performance and elasticity. Then, γ-glycidoxypropyltrimethoxysilane is added, which can promote the synergistic effect of each component, increasing the bonding strength of the damping adhesive without reducing its storage stability, and further improving its bonding performance. At the same time, it also gives it high storage stability. Finally, calcium carbonate is added as a reinforcing filler, a crosslinking agent is added as a vulcanizing agent, and a curing agent is added to promote the curing of the resin.

[0010] Preferably, the damping adhesive comprises the following components by weight: 10-20 parts by weight of nitrile rubber, 2-10 parts by weight of butadiene rubber, 5-10 parts by weight of epoxy resin, 2-7 parts by weight of PVC paste resin, 0.2-1 parts by weight of γ-glycidyl etheroxypropyltrimethoxysilane, 25-36 parts by weight of calcium carbonate, 0.1-0.5 parts by weight of crosslinking agent, and 0.1-1 parts by weight of curing agent.

[0011] The nitrile rubber can be 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, or 19 parts by weight, etc.

[0012] The butadiene rubber can be 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, or 9.5 parts by weight, etc.

[0013] The epoxy resin can be 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, or 9.5 parts by weight, etc.

[0014] The PVC paste resin can be 3 parts by weight, 4 parts by weight, 5 parts by weight, or 6 parts by weight, etc.

[0015] The γ-glycidyl etheroxypropyltrimethoxysilane may be in the form of 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, or 0.9 parts by weight.

[0016] The calcium carbonate may be in quantities of 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, or 35 parts by weight.

[0017] The crosslinking agent can be 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight, etc.

[0018] The curing agent can be 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, or 0.9 parts by weight, etc.

[0019] Preferably, the calcium carbonate includes heavy calcium carbonate and nano-activated calcium carbonate.

[0020] As a preferred technical solution of the present invention, the combination of heavy calcium carbonate and nano-activated calcium carbonate can make the shock-absorbing adhesive have better performance. If only heavy calcium carbonate is added, the surface of the shock-absorbing adhesive will not be fine and the density will increase because the particle size of heavy calcium carbonate is large. If only nano-activated calcium carbonate is added, the cost will increase.

[0021] Preferably, the mass ratio of the heavy calcium carbonate to the nano-active calcium carbonate is (1-3):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1 or 2.8:1, etc.

[0022] Preferably, the crosslinking agent is a peroxide crosslinking agent.

[0023] Preferably, the peroxide crosslinking agent includes any one or a combination of at least two of dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, or dicumyl peroxide.

[0024] Preferably, the curing agent comprises any one or a combination of at least two of dicyandiamide, 2-methylimidazole, 2-ethyl-4-methylimidazole or 2-phenylimidazole.

[0025] Preferably, the raw materials for preparing the shock-absorbing adhesive also include a water-absorbing agent and / or a plasticizer.

[0026] Preferably, the content of water-absorbing agent in the raw materials for preparing the shock-absorbing adhesive is 0.5 to 2 parts by weight, such as 0.7 parts by weight, 0.9 parts by weight, 1.1 parts by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight, or 1.9 parts by weight.

[0027] Preferably, the absorbent includes calcium oxide.

[0028] Preferably, the plasticizer content in the raw materials for preparing the shock-absorbing adhesive is 20 to 40 parts by weight, such as 22 parts by weight, 24 parts by weight, 26 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, or 38 parts by weight.

[0029] Preferably, the plasticizer comprises any one or a combination of at least two of dioctyl phthalate, dimethyl phthalate, diethyl phthalate, diisononyl phthalate, dihexyl phthalate, or di-n-butyl phthalate.

[0030] Preferably, the raw materials for preparing the shock-absorbing adhesive further include foaming agents and / or reinforcing agents.

[0031] Preferably, the content of foaming agent in the raw materials for preparing the shock-absorbing adhesive is 1 to 5 parts by weight, such as 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight or 4.5 parts by weight, etc.

[0032] Preferably, the foaming agent includes zinc oxide.

[0033] Preferably, the reinforcing agent content in the raw materials for preparing the damping adhesive is 0.2 to 14 parts by weight, such as 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, or 13 parts by weight.

[0034] Preferably, the reinforcing agent comprises any one or a combination of at least two of carbon black, silica, magnesium carbonate, or short fibers.

[0035] Preferably, the raw materials for preparing the shock-absorbing adhesive also include a foaming agent and / or an anti-aging agent.

[0036] Preferably, the foaming agent content in the raw materials for preparing the shock-absorbing adhesive is 0.1 to 0.5 parts by weight, such as 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight.

[0037] Preferably, the content of anti-aging agent in the raw materials for preparing the shock-absorbing adhesive is 0.1 to 0.5 parts by weight, such as 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight.

[0038] In a second aspect, the present invention provides a method for preparing the damping adhesive as described in the first aspect, the method comprising: mixing nitrile rubber, cis-butadiene rubber, epoxy resin, PVC paste resin, γ-glycidyl etheroxypropyltrimethoxysilane, calcium carbonate, crosslinking agent, curing agent, optionally water absorbent, optionally plasticizer, optionally foaming agent, optionally reinforcing agent, optionally foaming agent and optionally anti-aging agent to obtain the damping adhesive.

[0039] Thirdly, the present invention provides an application of the damping adhesive as described in the first aspect in the bonding of metal sheets.

[0040] Preferably, the metal sheet includes an aluminum sheet, a zinc sheet, or a steel sheet.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The raw materials for preparing the damping adhesive provided by this invention include styrene-butadiene rubber, nitrile rubber, epoxy resin, PVC paste resin, γ-glycidoxypropyltrimethoxysilane, calcium carbonate, crosslinking agent, and curing agent. By selecting styrene-butadiene rubber and nitrile rubber in combination, and supplementing them with epoxy resin and PVC paste resin, the damping adhesive has excellent bonding performance and elasticity. Further addition of γ-glycidoxypropyltrimethoxysilane can promote synergy among other components, increasing the bonding strength of the damping adhesive without reducing its storage stability. The resulting damping adhesive has excellent adhesion, heat resistance, water resistance, weather resistance, and storage stability, making it suitable for bonding metal sheets. Detailed Implementation

[0043] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0044] Examples 1-10

[0045] A shock-absorbing adhesive, the specific components of which are contained in its raw materials are shown in Table 1, and the amount of each component is in "parts by weight":

[0046] Table 1

[0047]

[0048]

[0049] The preparation method of the damping adhesive provided in Examples 1-10 includes: under the condition of cooling water circulation, kneading rubber, epoxy resin, PVC paste resin, silane coupling agent, calcium carbonate, crosslinking agent, curing agent, water absorbent, plasticizer, foaming aid, reinforcing agent, foaming agent and anti-aging agent in a kneader for 2 hours to obtain the damping adhesive.

[0050] Comparative Examples 1-9

[0051] A shock-absorbing adhesive, the components of which are listed in Table 2, are provided in "parts by weight":

[0052] Table 2

[0053]

[0054]

[0055] The preparation method of the damping adhesive provided in Comparative Examples 1 to 9 includes: kneading rubber, resin, silane coupling agent, calcium carbonate, crosslinking agent, curing agent, water absorbent, plasticizer, foaming agent, reinforcing agent, foaming agent and anti-aging agent in a kneader for 2 hours under the condition of cooling water circulation to obtain the damping adhesive.

[0056] Performance testing:

[0057] (1) Storage stability: After the pressure viscosity of the sample has been measured, it is placed at a constant temperature of 40℃ for 168h and then placed under standard conditions for 60min. Then the rotational viscosity is measured again and the viscosity change rate is calculated.

[0058] (2) Sample preparation: Shear module sample: Prepare an oil test sample substrate with a size of 100×25×1mm, apply the sample adhesive to the sample with a coating area of ​​25×25mm and an adhesive layer thickness of 2mm, then overlap and stack another sample of the same size with it, scrape off the excess sample adhesive, clamp it from both sides with two clamps, put it in a high temperature oven at 175℃ for 20min, take it out, and place it at room temperature for the following tests;

[0059] Shear strength: After the shear module is cured, the strength is tested after being placed in an environment of (23±2)℃ for 24 hours;

[0060] Water resistance: After the shear module is cured, it is placed in water at 30℃ for 168 hours and then placed at (23±2)℃ for 24 hours to test the shear strength.

[0061] Moist heat aging resistance: After the shear module is cured, it is placed in an aging test chamber at 85℃ and 85%RH for 168h, and then placed at (23±2)℃ for 24h before the shear strength is tested.

[0062] Salt spray resistance: After the shear module is cured, it is placed in a salt spray test chamber with sodium chloride content of 5% at 30℃ for 500h, and then placed at (23±2)℃ for 24h before the shear strength is tested.

[0063] The shock-absorbing adhesives provided in Examples 1-9 and Comparative Examples 1-8 were tested according to the above test methods. The test results are shown in Table 3.

[0064] Table 3

[0065] Storage stability / % Shear strength / MPa Water resistance / MPa Resistance to damp heat aging / MPa Salt spray resistance / MPa Example 1 17.6 0.88 0.32 0.86 0.78 Example 2 19.2 0.79 0.22 0.72 0.55 Example 3 27.9 1.02 0.31 0.89 0.85 Example 4 20.2 0.90 0.30 0.87 0.79 Example 5 21.4 0.66 0.24 0.65 0.57 Example 6 21.8 0.76 0.26 0.72 0.69 Example 7 21.5 0.90 0.26 0.89 0.80 Example 8 23.5 0.70 0.20 0.59 0.53 Example 9 15.8 0.56 0.13 0.46 0.44 Example 10 46.9 0.64 0.17 0.61 0.58 Comparative Example 1 27.8 0.41 0.11 0.36 0.28 Comparative Example 2 13.6 0.29 0.07 0.22 0.21 Comparative Example 3 27.9 0.56 0.12 0.50 0.43 Comparative Example 4 17.9 0.43 0.16 0.30 0.29 Comparative Example 5 42.9 0.81 0.27 0.73 0.61 Comparative Example 6 25.6 0.55 0.12 0.42 0.35 Comparative Example 7 26.6 0.49 0.12 0.40 0.33 Comparative Example 8 26.9 0.52 0.11 0.39 0.37 Comparative Example 9 27.3 0.24 0.07 0.21 0.15

[0066] According to the data in Table 3:

[0067] The damping adhesives obtained in Examples 1-3 exhibit excellent storage stability, with a viscosity conversion rate of 17.6-27.9%, a shear strength of 0.79-1.02 MPa at room temperature, a shear strength of 0.22-0.32 MPa after water treatment, a shear strength of 0.72-0.89 MPa after damp heat aging, and a shear strength of 0.55-0.85 MPa after salt spray treatment. They also demonstrate excellent water resistance, resistance to damp heat aging, and resistance to salt spray.

[0068] Comparing the data of Example 1 and Comparative Examples 1-4, it can be seen that the damping rubbers obtained by using a combination of nitrile rubber and styrene-butadiene rubber (Comparative Example 1), a combination of butadiene rubber and styrene-butadiene rubber (Comparative Example 2), using only nitrile rubber (Comparative Example 3), or using only butadiene rubber (Comparative Example 4) cannot simultaneously possess excellent storage stability and high shear strength.

[0069] Comparing the data from Example 1 and Comparative Examples 5-6, it can be seen that replacing γ-glycidoxypropyltrimethoxysilane with γ-aminopropyltriethoxysilane as the silane coupling agent results in a significant decrease in the storage stability of the obtained damping adhesive, which fails to meet the requirements; while replacing γ-glycidoxypropyltrimethoxysilane with γ-methacryloyloxypropyltrimethoxysilane as the silane coupling agent results in a decrease in the shear properties of the obtained damping adhesive.

[0070] Further comparison of the data from Example 1 and Comparative Examples 7-9 reveals that the absence of silane coupling agent (Comparative Example 7), PVC paste resin (Comparative Example 8), and epoxy resin (Comparative Example 9) all significantly affect the shear properties of the final damping adhesive.

[0071] Finally, comparing the data from Examples 1 and 4-10, it can be found that the amount of nitrile rubber and butadiene rubber added (Examples 4-5), the type and combination of calcium carbonate (Examples 6-7), the amount of epoxy resin added (Example 8), and the amount of silane coupling agent added (Examples 9-10) also affect the storage stability and shear strength of the obtained damping adhesive.

[0072] The applicant declares that this invention illustrates a shock-absorbing adhesive, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials in the product of this invention, the addition of auxiliary components, and the selection of specific methods, all fall within the protection and disclosure scope of this invention.

Claims

1. A shock absorbing gel, characterized in that, The raw materials for preparing the shock-absorbing adhesive include the following components by weight: 10-18 parts by weight of nitrile rubber, 5-10 parts by weight of cis-butadiene rubber, 5-10 parts by weight of epoxy resin, 2-7 parts by weight of PVC paste resin, 0.2-0.6 parts by weight of γ-glycidyl etheroxypropyltrimethoxysilane, 25-35 parts by weight of calcium carbonate, 0.1-0.5 parts by weight of crosslinking agent, and 0.1-1 parts by weight of curing agent; The calcium carbonate is heavy calcium carbonate and nano-active calcium carbonate with a mass ratio of (1~3):1; The damping adhesive has a shear strength of 0.79~1.02 MPa at room temperature, 0.22~0.32 MPa after water treatment, 0.72~0.89 MPa after damp heat aging, and 0.55~0.85 MPa after salt spray treatment.

2. The damping gum of claim 1, wherein The crosslinking agent is a peroxide crosslinking agent.

3. The damping gum of claim 2, wherein The peroxide crosslinking agent includes any one or a combination of at least two of dicumyl peroxide, benzoyl peroxide, di-tert-butyl peroxide, or dicumyl peroxide.

4. The damping gum of claim 1, wherein The curing agent includes any one or a combination of at least two of dicyandiamide, 2-methylimidazole, 2-ethyl-4-methylimidazole, or 2-phenylimidazole.

5. The damping gum of claim 1, wherein The raw materials for preparing the shock-absorbing adhesive also include water-absorbing agents and / or plasticizers.

6. The shock-absorbing adhesive according to claim 5, characterized in that, The content of water-absorbing agent in the raw materials for preparing the shock-absorbing adhesive is 0.5 to 2 parts by weight.

7. The damping adhesive according to claim 5, characterized in that, The absorbent includes calcium oxide.

8. The damping adhesive according to claim 5, characterized in that, The plasticizer content in the raw materials for preparing the shock-absorbing adhesive is 20-40 parts by weight.

9. The damping adhesive according to claim 5, characterized in that, The plasticizer includes any one or a combination of at least two of the following: dioctyl phthalate, dimethyl phthalate, diethyl phthalate, diisononyl phthalate, dihexyl phthalate, or di-n-butyl phthalate.

10. The shock-absorbing adhesive according to claim 1, characterized in that, The raw materials for preparing the damping adhesive also include foaming agents and / or reinforcing agents.

11. The shock-absorbing adhesive according to claim 10, characterized in that, The foaming agent content in the raw materials for preparing the shock-absorbing adhesive is 1 to 5 parts by weight.

12. The shock-absorbing adhesive according to claim 10, characterized in that, The foaming agent includes zinc oxide.

13. The shock-absorbing adhesive according to claim 10, characterized in that, The reinforcing agent content in the raw materials for preparing the damping adhesive is 0.2 to 14 parts by weight.

14. The shock-absorbing adhesive according to claim 10, characterized in that, The reinforcing agent includes any one or a combination of at least two of carbon black, silica, magnesium carbonate, or short fibers.

15. The shock-absorbing adhesive according to claim 1, characterized in that, The raw materials for preparing the shock-absorbing adhesive also include foaming agents and / or anti-aging agents.

16. The shock-absorbing adhesive according to claim 15, characterized in that, The foaming agent content in the raw materials for preparing the shock-absorbing adhesive is 0.1~0.5 parts by weight.

17. The shock-absorbing adhesive according to claim 15, characterized in that, The anti-aging agent content in the raw materials for preparing the shock-absorbing adhesive is 0.1~0.5 parts by weight.

18. A method for preparing a damping adhesive as described in any one of claims 1 to 17, characterized in that, The preparation method includes: mixing nitrile rubber, cis-butadiene rubber, epoxy resin, PVC paste resin, γ-glycidoxypropyltrimethoxysilane, calcium carbonate, crosslinking agent, curing agent, optionally water absorbent, optionally plasticizer, optionally foaming agent, optionally reinforcing agent, optionally foaming agent and optionally anti-aging agent to obtain the shock-absorbing adhesive.

19. The method for preparing the damping adhesive according to claim 18, characterized in that, The mixing takes place under conditions of cooling water circulation.

20. The method for preparing the damping adhesive according to claim 18, characterized in that, The mixing is carried out in a kneader.

21. The method for preparing the damping adhesive according to claim 18, characterized in that, The mixing time is 1 to 3 hours.

22. The application of a damping adhesive as described in any one of claims 1 to 17 in the bonding of metal sheets.

23. The application according to claim 22, characterized in that, The metal sheet includes aluminum sheet, zinc sheet, or steel sheet.

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