Micro-foamed silicone rubber cell cushion strip-shaped material and preparation process

Abstract

The application discloses a kind of micro-foaming silicon rubber battery core buffer strip-shaped materials and preparation process, it is related to silicon rubber technical field.A kind of micro-foaming silicon rubber battery core buffer strip-shaped material is constituted by the following mass ratio of components: methyl vinyl silicone rubber raw rubber: 90-100 parts, reinforcing filler: 35-50 parts, structure control agent: 2-5 parts, foaming agent: 3-8 parts, vulcanizing agent: 0.5-2 parts, auxiliary crosslinking agent: 0.5-3 parts, flame retardant: 1-3 parts, antioxidant: 0.5-1.5 parts.The application effectively delays the aging process of material in high temperature, oxidation environment by the addition of specific antioxidant, maintains the toughness and strength of material, and simultaneously each group cooperates, makes material foaming uniformity improve, improves the mechanical properties of material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone rubber, in particular to a micro-foamed silicone rubber battery core buffer strip-shaped material and a preparation process thereof. BACKGROUND

[0002] In the application of battery cores in modern electronic devices, buffer materials are crucial as they can alleviate the impact of external shocks, vibrations, and internal temperature changes on the battery core, prevent mechanical damage and poor contact, and ensure stable operation of the battery core. Currently, traditional rubber is commonly used as a buffer material on the market, but it has many defects: long-term use or high temperature can cause aging, leading to a decrease in buffer performance, uneven foaming resulting in defects in the microstructure, poor mechanical properties that cannot meet the high load impact requirements, and poor fire resistance and heat resistance. These problems accelerate the failure of the battery core and even pose a safety hazard.

[0003] Micro-foamed silicone rubber has attracted attention due to its unique properties, as its micro-porous structure improves buffer performance and mechanical strength, and it is temperature-stable and resistant to aging. However, there is still room for improvement in the selection of foaming agents, the ratio of structure control agents, and the optimization of vulcanization processes for existing micro-foamed silicone rubber materials, which limits their application in the field of high-end electronic device battery core buffers.

[0004] Therefore, it is particularly urgent to develop an improved micro-foamed silicone rubber battery core buffer strip-shaped material and a preparation process thereof, optimize the material formula and process flow, and overcome the problems of insufficient aging performance, low foaming efficiency, and poor mechanical properties of existing technologies. SUMMARY

[0005] The present application aims to solve the problems of high-temperature aging, insufficient heat and weather resistance, and poor mechanical properties of existing battery core buffer materials, and provides an optimized micro-foamed silicone rubber battery core buffer strip-shaped material and a preparation process thereof. Through specific formula components and process optimization, the material's aging resistance and mechanical strength are significantly improved, making it suitable for impact and vibration protection of electronic device battery cores.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a micro-foamed silicone rubber battery core buffer strip-shaped material, which is composed of the following components in mass ratio: methyl vinyl silicone rubber raw rubber: 90-100 parts, reinforcing filler: 35-50 parts, structure control agent: 2-5 parts, foaming agent: 3-8 parts, vulcanizing agent: 0.5-2 parts, co-crosslinking agent: 0.5-3 parts, flame retardant: 1-3 parts, anti-aging agent: 0.5-1.5 parts;

[0007] The anti-aging agent is a compound of formula 1:

[0008] Formula 1: ;

[0009] R1in the formula 1 is a substituent selected from the group consisting of methyl, cyano, carboxyl, methoxy.

[0010] Further, the reinforcing filler is fumed white carbon black.

[0011] Further, the structure control agent is at least one of hydroxyl silicone oil, dimethyl diethoxysilane or hexamethyl disilazane.

[0012] Further, the foaming agent is at least one of 4,4'-oxybisbenzenesulfonylhydrazide, azodicarbonamide or N,N'-dinitrosopentamethylenetetramine.

[0013] Further, the vulcanizing agent is at least one of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, dicumyl peroxide or 2,4-dichlorobenzoyl peroxide.

[0014] Further, the co-crosslinking agent is at least one of triallyl isocyanurate or trimethylolpropane trimethacrylate; the flame retardant is at least one of aluminum hydroxide or magnesium hydroxide.

[0015] Further, the antioxidant is selected from one or more combinations of compounds shown in the following structures:

[0016] ;

[0017] .

[0018] A preparation method of a micro-foamed silicone rubber battery core buffer strip-shaped material, comprising the following steps:

[0019] a. Put the raw methyl vinyl silicone rubber into a mixing mill, add the structure control agent and reinforcing filler, and mix at 60-80°C to obtain a silicone rubber compound;

[0020] b. After cooling the silicone rubber compound, put it into an open mill for re-mixing, add the foaming agent, vulcanizing agent, co-crosslinking agent, flame retardant and antioxidant, control the roller temperature below 60°C, and pass through 6-8 times to obtain a mixed compound;

[0021] c. Extrude the mixed compound through an extruder to obtain a strip-shaped rubber blank;

[0022] d. Put the strip-shaped rubber blank into a continuous vulcanization production line, vulcanize and foam at 160-180°C for 10-20 minutes for primary vulcanization, transfer the foamed strip after primary vulcanization into a high-temperature oven, and perform secondary vulcanization at 180-200°C for 2-4 hours, and after cooling, obtain a micro-foamed silicone rubber battery core buffer strip-shaped material.

[0023] Further, the temperature of the head of the extruder in step c is controlled at 40-60℃, and the screw rotation speed is 10-30 rpm.

[0024] Further, the first vulcanization and foaming process in step d is carried out under pressure, and the pressure range is 0.2-0.8 MPa.

[0025] The anti-aging agent molecules can effectively neutralize the free radicals generated by the silicon rubber under the action of heat, oxygen or stress, prevent the polymer chain from breaking and degrading, and thus delay the hardening, cracking or performance degradation of the material. In the working environment of the battery, the silicon rubber is easy to produce free radical chain reaction under the action of heat or oxidation, resulting in molecular chain rupture. The active groups in the anti-aging agent can efficiently capture free radicals as electron acceptors, interrupting the oxidation reaction chain. The molecular structure of the anti-aging agent contains polycyclic or heteroatom groups, providing stronger electron transfer ability. In the vulcanization and foaming process, the active sites in the molecule physically adsorb or weakly chemically bond with the methyl vinyl chain segments of the raw rubber of the silicon rubber, forming a protective layer. This reduces the thermal oxidation side reaction during high-temperature vulcanization, ensuring uniform foaming structure. Under dynamic load, the anti-aging agent absorbs mechanical energy and disperses stress, preventing the expansion of microcracks and improving the fatigue resistance of the material.

[0026] Methyl vinyl silicone rubber gum as a material matrix provides flexibility, elasticity and basic temperature resistance. Its siloxane backbone imparts inherent heat resistance to the material, forms a crosslinked network with other components (such as fillers and vulcanizing agents) as a buffer skeleton. After synergistic antioxidant, reduce chain scission at high temperature, delay aging. Reinforcing fillers mainly enhance mechanical properties, improve wear resistance and impact resistance. High specific surface area white carbon black is dispersed in the silicone rubber matrix by physical adsorption and chemical bonding, fills micropores and strengthens the material. Structure control agent controls the dispersion of fillers and the foaming structure, prevents micro defects, in the mixing stage, the structure control agent is adsorbed on the surface of white carbon black, reduces the hydrogen bond effect, avoids the aggregation of fillers, cooperates with the foaming agent to optimize the pore structure; Cooperate with vulcanizing agent to maintain dimensional stability at high temperature. Foaming agent generates micro-porous structure to improve the energy absorption performance of buffer, in the vulcanization stage, the foaming agent decomposes to produce gas, forming a closed microstructure. Cooperate with pressure control, gas diffusion is uniform, avoid large pores or collapse defects in traditional foaming. Linkage with structure control agent, ensure uniform distribution of gas; Synchronous reaction with vulcanizing agent, prevent premature foaming leading to strength loss. Vulcanizing agent can initiate crosslinking reaction, enhance heat resistance and mechanical strength. In the segmented vulcanization process, the vulcanizing agent decomposes to produce free radicals, promoting the crosslinking of silicone rubber molecular chains, improving the hardness, tear resistance and high temperature stability of the material, solving the problems of poor mechanical properties and aging. Cooperate with antioxidant to reduce high temperature free radical damage. Co-crosslinking agent can assist vulcanization, improve crosslinking efficiency and uniformity. Multi-functional co-crosslinking agent cooperates with vulcanizing agent to increase the density of crosslinking points, shorten the vulcanization time and reduce energy consumption, strengthen the skeleton of the micro-porous structure, improve the impact resistance, solve the problem of insufficient mechanical properties. Form a "catalyst-co-agent" system with vulcanizing agent; Linkage with reinforcing fillers to enhance overall rigidity. When the flame retardant decomposes under heat, it can absorb a large amount of heat, reducing the surface temperature of the silicone rubber and preventing it from continuing to burn. Antioxidants can inhibit high-temperature oxidation and degradation, prolonging the service life of the material. The chemical properties of each component and the process design cooperate with each other, optimizing the material composition, microstructure and macroscopic performance, significantly improving the cushioning performance, aging resistance and mechanical strength of the material, meeting the cushioning requirements of high-end electronic device batteries.

[0027] Compared with the prior art, the beneficial effects of the present application are:

[0028] 1. The aging resistance is significantly improved: through the addition and synergistic effect of specific antioxidants, the aging process of the material in high temperature and oxidative environment is effectively delayed, maintaining the toughness and strength of the material.

[0029] 2. The mechanical properties are effectively improved: the synergistic effect of silicone rubber gum matrix, reinforcing fillers, vulcanizing agents and co-crosslinking agents improves the uniformity of material foaming, enhances the impact resistance, and stabilizes the overall hardness and tensile properties.

[0030] 3. The flame-retardant performance remains stable: while improving the material formula and process, the synergistic effect of the flame retardant and the antioxidant ensures that the fireproof performance of the material is not affected, and always meets the flame-retardant requirements of electronic equipment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The antioxidant 1 described in the present application is 1 HNMR chart. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] Synthesis Example 1:

[0034] Synthesis of antioxidant 1:

[0035] ;

[0036] First step: under a nitrogen atmosphere, 20.00 g of raw material 1, 22.80 g of raw material 2, 30.01 g of potassium carbonate, 0.24 g of palladium acetate, 1.10 g of tri-tert-butyl phosphine and 300 g of toluene are sequentially added into the reaction system, stirred uniformly, heated to 110°C, and refluxed for 12 h; after the reaction is completed, the temperature is slightly lowered, diatomite is used for filtration, the filtrate is cooled to room temperature, washed with water three times, the organic phase is reserved, and then the aqueous phase is extracted with ethyl acetate; after the organic phases are combined, anhydrous magnesium sulfate is used for drying, filtration, rotary evaporation, and silica gel column chromatography is performed with a mixture of petroleum ether and ethyl acetate as the eluent, rotary evaporation is performed, and 19.05 g of intermediate 1 is obtained.

[0037] Second step: 19.05 g of intermediate 1 is placed in a two-necked flask, 250 mL of dichloromethane is added under nitrogen protection, and then 25.42 g of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate is added, stirred at room temperature for 1 h. 14.79 g of raw material 3 is dissolved in 50 mL of dichloromethane and added to the above system, then 7.86 g of N,N-diisopropyl ethylamine is added under an ice water bath, the ice water bath is removed, and the system is stirred at room temperature overnight. After treatment, 300 mL of dichloromethane is added, washed with 1M hydrochloric acid aqueous solution three times, washed with saturated sodium bicarbonate aqueous solution three times, and the organic phase is washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and silica gel column chromatography is performed with a mixture of petroleum ether and ethyl acetate as the eluent, rotary evaporated, and 16.47 g of antioxidant 1 is obtained. The HNMR chart of antioxidant 1 is shown in 1 HNMR chart.Figure 1 .

[0038] Structure identification:

[0039] Mass spectrum M / Z (MS+1) of intermediate 1: 314;

[0040] Mass spectrum M / Z (MS+1) of anti-aging agent 1: 539;

[0041] Mass spectrum M / Z (MS+1) of anti-aging agent 1: 1 HNMR δ 9.21 (s, 2H), 7.96-7.85 (m, 2H), 7.68-7.55 (m, 3H), 7.33-7.17 (m, 9H), 7.15-7.06 (m, 4H), 7.02-6.89 (m, 4H), 3.78 (s, 3H), 2.40 (s, 3H).

[0042] Synthesis examples 2-4:

[0043] Anti-aging agents 2-4 were synthesized in synthesis examples 2-4 in turn, and the synthesis method of synthesis example 1 was referred to, and raw material 2 therein was replaced, and the rest was the same as synthesis example 1. The structure of raw material 2, the structure of anti-aging agents 2-4, and the mass spectrum M / Z (MS+1) data are shown in Table 1.

[0044] Table 1 Structure of raw material 2, structure of anti-aging agents 2-4, and mass spectrum M / Z (MS+1) data involved in synthesis examples 2-4

[0045]

[0046] Example 1:

[0047] Preparation of a micro-foamed silicone rubber cell buffer strip-shaped material:

[0048] 1. Raw material mass ratio:

[0049] Methyl vinyl silicone rubber raw rubber: 95 parts, purchased from Yichang Xingyue New Material Co., Ltd.;

[0050] Reinforcing filler: 40 parts, selected from fumed white carbon black, purchased from Shandong Haoyang Star Chemical Technology Co., Ltd.;

[0051] Structure control agent: 4 parts, selected from hydroxyl silicone oil, purchased from Shandong Longhui Chemical Co., Ltd.;

[0052] Foaming agent: 5 parts, selected from 4,4'-oxobenzene sulfonyl hydrazine, purchased from Hangzhou Jieheng Chemical Co., Ltd., CAS: 80-51-3;

[0053] Vulcanizing agent: 1 part, selected from: 2,4-dichlorobenzoyl peroxide, purchased from: Hubei Chengfeng Chemical Co., Ltd., CAS: 133-14-2;

[0054] Co-crosslinking agent: 2 parts, selected from: triallyl isocyanurate, purchased from: Hubei Qifei Pharmaceutical Chemical Co., Ltd., CAS: 1025-15-6;

[0055] Flame retardant: 2 parts, selected from: aluminum hydroxide, purchased from: Yangzhou Zhongtianli New Material Co., Ltd.;

[0056] Anti-aging agent: 1 part, selected from the anti-aging agent 1 synthesized in Synthesis Example 1.

[0057] 2. Preparation method:

[0058] a. 95 parts of methyl vinyl silicone rubber raw rubber were put into a mixer, 4 parts of structure control agent and 40 parts of reinforcing filler were added, and mixed at 75℃ for 30 minutes until the filler was uniformly dispersed, to obtain a silicone rubber compound;

[0059] b. The silicone rubber compound was cooled to room temperature and transferred to an open mill for re-mixing, 5 parts of foaming agent, 1 part of vulcanizing agent, 2 parts of co-crosslinking agent, 2 parts of flame retardant and 1 part of anti-aging agent were added, and the roller temperature was controlled at 50℃, and the compound was passed through the mill 7 times to obtain a mixed compound;

[0060] c. The mixed compound was extruded by an extruder, the die temperature was controlled at 50℃, and the screw rotation speed was 20 rpm, and a strip-shaped rubber blank was obtained by extrusion;

[0061] d. The strip-shaped rubber blank was sent into a continuous vulcanization production line, and one-stage vulcanization foaming was carried out at a pressure of 0.5 MPa and a temperature of 170℃ for 15 minutes, then transferred into a high temperature oven, and two-stage vulcanization was carried out at 190℃ for 3 hours, and cooled to room temperature to obtain a micro-foamed silicone rubber battery core buffer strip-shaped material.

[0062] Examples 2-4:

[0063] A micro-foamed silicone rubber battery core buffer strip-shaped material was prepared by referring to the preparation method of Example 1, and the anti-aging agent therein was replaced by the anti-aging agents 2-4 prepared in Synthesis Examples 2-4, respectively, and the rest was the same as Example 1.

[0064] Comparative Example 1:

[0065] A micro-foamed silicone rubber battery core buffer strip-shaped material was prepared by referring to the preparation method of Example 1, and the anti-aging agent therein was not added, and the rest was the same as Example 1.

[0066] Comparative Example 2:

[0067] A kind of micro-foaming silicone rubber battery core buffer strip-shaped material is prepared, referring to the preparation method of example 1, the mass fraction of reinforcing filler therein is replaced by 60 parts, and the rest remains the same as example 1.

[0068] Comparative example 3:

[0069] A kind of micro-foaming silicone rubber battery core buffer strip-shaped material is prepared, referring to the preparation method of example 1, the anti-aging agent therein is replaced by anti-aging agent DTPD, CAS: 27417-40-9, and the rest remains the same as example 1.

[0070] Comparative example 4:

[0071] A kind of micro-foaming silicone rubber battery core buffer strip-shaped material is prepared, referring to the preparation method of example 1, the anti-aging agent therein is replaced by anti-aging agent 4010NA, CAS: 101-72-4, and the rest remains the same as example 1.

[0072] Comparative example 5:

[0073] A kind of micro-foaming silicone rubber battery core buffer strip-shaped material is prepared, referring to the preparation method of example 1, the anti-aging agent therein is replaced by comparative compound 1: , and the rest remains the same as example 1.

[0074] Performance test:

[0075] 1. Tensile strength: the tensile strength of a micro-foaming silicone rubber battery core buffer strip-shaped material prepared in the example and comparative example is tested according to GB / T1701-2001 standard, and the results are shown in table 2.

[0076] 2. Shore A hardness: the Shore A hardness of a micro-foaming silicone rubber battery core buffer strip-shaped material prepared in the example and comparative example is tested according to GB / T531.1-2008 standard, and the results are shown in table 2.

[0077] 3. Flame retardant performance: the flame retardant performance of a micro-foaming silicone rubber battery core buffer strip-shaped material prepared in the example and comparative example is tested according to UL94 standard, and the results are shown in table 2.

[0078] 4. Tensile strength after aging: a micro-foaming silicone rubber battery core buffer strip-shaped material prepared in the example and comparative example is placed in a xenon lamp aging test box, exposed for 4800 hours, and then its tensile strength is tested according to GB / T1701-2001, and the results are shown in table 2.

[0079] Exposure conditions: radiation intensity: 0.35 W / m 2(340 nm wavelength); temperature cycle: 80 °C (light phase) to 20 °C (dark phase), 8 hours light + 4 hours condensation per cycle (simulated rain); relative humidity: 50% ± 5% (light phase), 95% ± 5% (condensation phase).

[0080] Table 2. Performance test results of one micro-foamed silicone rubber cell cushion strip material prepared in examples and comparative examples

[0081]

[0082] From the performance test results in Table 2, it can be seen that the specific antioxidant used in the examples of the present application significantly improves the anti-aging performance of the material, which is reflected in the excellent tensile strength after aging, far superior to the comparative examples without adding antioxidant or using other types of antioxidant. At the same time, the examples show stable and high performance in initial tensile strength and hardness, while the comparative examples with excessive reinforcing filler result in a significant decline in overall mechanical properties. The overall trend confirms the key advantages of the antioxidant design and component synergy of the present application in inhibiting high-temperature aging and maintaining material durability.

[0083] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A micro-foamed silicone rubber cell buffer strip material, characterized in that, It is composed of the following components in the indicated mass ratios: methyl vinyl silicone rubber raw rubber: 90-100 parts, reinforcing filler: 35-50 parts, structure control agent: 2-5 parts, foaming agent: 3-8 parts, vulcanizing agent: 0.5-2 parts, crosslinking agent: 0.5-3 parts, flame retardant: 1-3 parts, antioxidant: 0.5-1.5 parts; The antioxidant is a compound of formula 1: Formula 1: ; In Formula 1, R1 is a substituent selected from: methyl, cyano, carboxyl, and methoxy.

2. The microfoamed silicone rubber cell buffer strip material according to claim 1, characterized in that, The reinforcing filler is fumed silica.

3. The microfoamed silicone rubber cell buffer strip material according to claim 1, characterized in that, The structure control agent is at least one of hydroxyl silicone oil, dimethyldiethoxysilane, or hexamethyldisilazane.

4. The microfoamed silicone rubber cell buffer strip material according to claim 1, characterized in that, The foaming agent is at least one of 4,4'-oxobis(benzenesulfonyl)hydrazine, azodicarbonamide, or N,N'-dinitrospentamethylenetetramine.

5. The microfoamed silicone rubber cell buffer strip material according to claim 1, characterized in that, The vulcanizing agent is at least one of 2,5-dimethyl-2,5-di-tert-butylperoxide, dicumyl peroxide, or 2,4-dichlorobenzoyl peroxide.

6. The microfoamed silicone rubber cell buffer strip material according to claim 1, characterized in that, The crosslinking agent is at least one of triallyl isocyanurate or trimethylolpropane trimethacrylate; the flame retardant is at least one of aluminum hydroxide or magnesium hydroxide.

7. A method for preparing a micro-foamed silicone rubber cell buffer strip material according to any one of claims 1-6, characterized in that, Includes the following steps: a. The raw methyl vinyl silicone rubber is put into an internal mixer, the structure control agent and reinforcing filler are added, and the mixture is mixed at 60-80°C to obtain silicone rubber compound; b. After cooling the silicone rubber compound, put it into a two-roll mill for re-milling, add the foaming agent, vulcanizing agent, crosslinking agent, flame retardant and antioxidant, control the roller temperature below 60°C, and pass through the mill 6-8 times to obtain the mixed compound. c. The mixed rubber compound is extruded using an extruder to obtain a strip-shaped rubber preform; d. The strip-shaped rubber blank is fed into a continuous vulcanization production line and vulcanized and foamed at 160-180℃ for 10-20 minutes. After a first-stage vulcanization, the foamed strip after the first stage vulcanization is transferred to a high-temperature oven and vulcanized at 180-200℃ for 2-4 hours. After cooling, a micro-foamed silicone rubber battery cell buffer strip material is obtained.

8. The method for preparing a micro-foamed silicone rubber cell buffer strip material according to claim 7, characterized in that, In step c, the extruder head temperature is controlled at 40-60℃, and the screw speed is 10-30 rpm.

9. The method for preparing a micro-foamed silicone rubber cell buffer strip material according to claim 7, characterized in that, In step d, a vulcanization foaming process is carried out under pressure conditions, with a pressure range of 0.2-0.8 MPa.

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