Security lens rubber sealing material and preparation process thereof

Abstract

This invention relates to the field of sealing materials technology, specifically a rubber sealing material for security lenses and its preparation process. Alkali lignin nanoparticles are prepared using alkali lignin as a raw material, and then co-assembled with graphene oxide to obtain composite graphene oxide. This composite graphene oxide is then epoxidized with epichlorohydrin, followed by grafting of a fluorinated diamine compound using an epoxy-amine reaction. Using environmentally friendly materials oleic acid and 1,6-hexanediol as raw materials, esterification is first used to obtain the plasticizer 1,6-hexanediol oleate, which is then epoxidized. Following this, an epoxy-amine reaction is used to graft a fluorinated diamine compound, generating an oleic acid derivative as a plasticizer. Finally, epoxidized EPDM rubber is synthesized through in-situ epoxidation with formic acid and hydrogen peroxide as the raw material for EPDM rubber.

Description

Technical Field

[0001] This invention relates to the field of sealing materials technology, specifically a rubber sealing material for security cameras and its preparation process. Background Technology

[0002] Security cameras are the eyes of the security industry and an important component of security systems. As a key component of security cameras, the performance of the sealing components directly affects the image clarity and lifespan of the security cameras.

[0003] For example, when the waterproof properties of the sealing materials used in security lenses are poor, water droplets can condense on the lens in rainy, foggy, or snowy weather, causing image blurring. In hot weather, the limited heat resistance and sealing properties of the sealing materials used in security lenses may lead to the precipitation of oily substances from internal components, resulting in blurred images. Therefore, developing a sealing material for security lenses that is water-resistant, heat-resistant, and has good sealing properties is of practical significance and economic value. Summary of the Invention

[0004] The purpose of this invention is to provide a rubber sealing material for security cameras and its manufacturing process, so as to solve the problems in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A rubber sealing material for security lenses, by weight, comprises: 80 parts of composite EPDM rubber, 20 parts of silicone, 2-5 parts of activator, 12-18 parts of modified graphene oxide, 20-35 parts of plasticizer, 1-3 parts of accelerator, and 1-3 parts of vulcanizing agent; the silicone is obtained by compounding fumed silica and precipitated silica in a mass ratio of 1:1.

[0007] Furthermore, the activator is a mixture of zinc oxide, stearic acid, and itaconic acid in a mass ratio of 4:1:1.

[0008] Furthermore, the accelerator is one or more of 2-mercaptobenzothiazole, N,N'-diphenyl-thiourea, and N-cyclohexyl-2-benzothiazole sulfenamide.

[0009] Furthermore, the composite EPDM rubber is obtained by compounding EPDM rubber and epoxidized EPDM rubber in a mass ratio of 1:1.

[0010] Furthermore, the preparation of epoxidized EPDM rubber includes the following steps:

[0011] Under a nitrogen atmosphere, EPDM rubber and n-hexane are mixed and kept at a temperature of 48-52℃ for 10-15 min. Formic acid and Tween 80 are added and stirred for 10-15 min. Hydrogen peroxide is added and kept at a temperature of 7-8 h. The mixture is washed with sodium carbonate aqueous solution, separated, washed with deionized water until neutral, added to anhydrous ethanol, and dried under vacuum to obtain epoxidized EPDM rubber.

[0012] Furthermore, the preparation of modified graphene oxide includes the following steps:

[0013] (1) Mix graphene oxide powder and ultrapure water, sonicate for 8-10 min, add alkali lignin and ultrapure water mixture, adjust pH to 9.9-10.1, centrifuge, vacuum filter and dry to obtain composite graphene oxide.

[0014] (2) Mix the composite graphene oxide and N,N-dimethylformamide, disperse by ultrasonication, add potassium fluoride and potassium iodide, stir for 10-15 min, add epichlorohydrin, heat to 98-102℃ and keep warm for 14-15 h, centrifuge, wash and freeze dry to obtain epoxidized composite graphene oxide.

[0015] (3) Under a nitrogen atmosphere, epoxidized composite graphene oxide, fluorinated diamine compound and dimethyl sulfoxide are mixed, heated to 105-110℃ and kept at the temperature for 3-4 hours, cooled, washed and dried to obtain modified graphene oxide.

[0016] Furthermore, the plasticizer is an oleic acid derivative.

[0017] Furthermore, the preparation of oleic acid derivatives includes the following steps:

[0018] 1) Under a nitrogen atmosphere, oleic acid and 1,6-hexanediol are mixed, concentrated sulfuric acid is added, the temperature is raised to 128-132℃ and kept at this temperature for 7-8 hours. The solution is washed with sodium bicarbonate until neutral, washed with water, and allowed to stand to obtain 1,6-hexanediol oleate. 1,6-hexanediol oleate, hydrogen peroxide solution, formic acid, and concentrated sulfuric acid are mixed and stirred at 58-62℃ for 7-8 hours. The solution is washed with deionized water until neutral and then rotary evaporated to obtain epoxy 1,6-hexanediol oleate.

[0019] 2) Under a nitrogen atmosphere, epoxy 1,6-hexanediol oleate, fluorinated diamine compound, and dimethyl sulfoxide are mixed, heated to 100-105℃ and held for 4-5 hours, cooled, washed, and dried to obtain oleic acid derivative.

[0020] Furthermore, the preparation of fluorinated diamine compounds includes the following steps:

[0021] Under a nitrogen atmosphere, p-trifluoromethylbenzaldehyde and 2,6-dimethylaniline were mixed and heated to 78-82°C. Hydrochloric acid solution was added, and the temperature was raised to 148-152°C and maintained for 23-24 hours. After cooling, sodium hydroxide solution was added, and the mixture was extracted 3-5 times with dichloromethane. The mixture was then washed 3-5 times with deionized water and saturated sodium chloride solution, rotary evaporated, and the precipitate was poured into methanol. The precipitate was filtered, washed, and dried to obtain a fluorinated diamine compound.

[0022] Furthermore, a preparation process for a rubber sealing material for security lenses includes the following steps: ethylene propylene diene monomer (EPDM) rubber and silicone rubber are put into a mixer, then modified graphene oxide, activator, and plasticizer are added sequentially, mixed, discharged, transferred to a two-roll mill, vulcanizing agent and accelerator are added, filtered, allowed to stand, and vulcanized to obtain a rubber sealing material for security lenses.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention provides a rubber sealing material for security cameras and its preparation process. By optimizing the composition and process design, a sealing material with good sealing performance, excellent water resistance, high temperature resistance, and aging resistance is prepared, which meets the requirements of security cameras for sealing materials.

[0025] In this invention, graphene oxide is selected as a reinforcing agent and lignin as an antioxidant. Alkali lignin nanoparticles are prepared using alkali lignin as a raw material, and then co-assembled with graphene oxide to obtain composite graphene oxide. To improve the uniformity of the composite graphene oxide dispersion in the rubber matrix, the composite graphene oxide is modified. First, it is epoxidized with epichlorohydrin, and then a fluorinated diamine compound is grafted using an epoxy-amino reaction. The fluorinated diamine compound is prepared from p-trifluoromethylbenzaldehyde and 2,6-dimethylaniline, introducing fluorine to improve its water resistance and thermal stability. At the same time, the introduction of multiple active sites on the modified graphene oxide helps to improve its interfacial compatibility with the rubber matrix, allowing graphene oxide and lignin to firmly adhere to the sealing material and improve its durability.

[0026] Most current chemical plasticizers suffer from problems such as high cost, poor migration resistance, and environmental unfriendliness. In this invention, environmentally friendly materials oleic acid and 1,6-hexanediol are used as raw materials. First, esterification is performed to obtain the plasticizer 1,6-hexanediol oleate, then epoxidation is performed, and then fluorinated diamine compounds are grafted using an epoxy-amine reaction to generate oleic acid derivatives with good water resistance and high thermal stability as plasticizers, thereby significantly improving the various properties of sealing materials.

[0027] In this invention, to reduce the amount of vulcanizing agent used, epoxidized EPDM rubber is first synthesized through in-situ epoxidation with formic acid-hydrogen peroxide as the raw material for EPDM rubber. Based on the reaction of epoxy with amino and carboxyl groups, a cross-linked network structure containing ester bonds is constructed with activator, modified graphene oxide and plasticizer. At the same time, the addition of zinc oxide in the activator can activate the epoxy groups, effectively improving its cross-linking efficiency and cross-linking density, thereby improving the various properties of the sealing material. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that if the embodiments of the present invention involve directional indicators such as up, down, left, right, front, and back, these directional indicators are only used to explain the relative positional relationship and movement of components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0030] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0031] Example 1: A preparation process of a rubber sealing material for security lenses, comprising the following steps: putting composite EPDM rubber and silicone into a mixer, then adding modified graphene oxide, activator and plasticizer in sequence, mixing, discharging the glue, transferring to a two-roll mill, adding vulcanizing agent and accelerator, filtering, standing and vulcanizing to obtain a rubber sealing material for security lenses;

[0032] The raw material composition of the sealing material, by weight, is as follows: 80 parts of composite EPDM rubber, 20 parts of silicone, 2 parts of activator, 12 parts of modified graphene oxide, 20 parts of plasticizer, 1 part of accelerator, and 1 part of vulcanizing agent; the silicone is obtained by compounding fumed silica and precipitated silica in a mass ratio of 1:1.

[0033] The activator is a compound of zinc oxide, stearic acid, and itaconic acid in a mass ratio of 4:1:1.

[0034] The accelerator is 2-mercaptobenzothiazole;

[0035] The composite EPDM rubber is obtained by blending EPDM rubber and epoxidized EPDM rubber in a mass ratio of 1:1.

[0036] The preparation of the epoxidized EPDM rubber includes the following steps:

[0037] Under a nitrogen atmosphere, 30g of EPDM rubber and 500mL of n-hexane were mixed and kept at 48℃ in a water bath for 15min. 0.6g of formic acid and 1.5g of Tween 80 were added and stirred for 10min. 5.1g of hydrogen peroxide was added and kept at this temperature for 7h. The mixture was washed with sodium carbonate aqueous solution, separated, washed with deionized water until neutral, added to 1L of anhydrous ethanol, and dried under vacuum to obtain epoxidized EPDM rubber.

[0038] The preparation of the modified graphene oxide includes the following steps:

[0039] (1) Mix 0.2g of graphene oxide powder and 150mL of ultrapure water, sonicate for 8min, add 2g of alkali lignin and 50mL of ultrapure water, adjust the pH value to 9.9, centrifuge, vacuum filter and dry to obtain composite graphene oxide.

[0040] (2) Mix 0.2g of composite graphene oxide and 100mL of N,N-dimethylformamide, disperse by ultrasonication, add 37.6g of potassium fluoride and 5g of potassium iodide, stir for 10min, add 20mL of epichlorohydrin, heat to 98℃ and keep warm for 15h, centrifuge, wash and freeze dry to obtain epoxidized composite graphene oxide.

[0041] (3) Under a nitrogen atmosphere, 5.3g of epoxidized composite graphene oxide, 2.2g of fluorinated diamine compound and 100mL of dimethyl sulfoxide were mixed, heated to 105℃ and kept at the temperature for 4h, cooled, washed and dried to obtain modified graphene oxide.

[0042] The plasticizer is an oleic acid derivative, and its preparation includes the following steps:

[0043] 1) Under a nitrogen atmosphere, 2.1 g of oleic acid and 5.9 g of 1,6-hexanediol were mixed, and 0.03 g of concentrated sulfuric acid was added. The mixture was heated to 128 °C and kept at that temperature for 8 h. The solution was washed with sodium bicarbonate until neutral, washed with water, and allowed to stand to obtain 1,6-hexanediol oleate. 0.6 g of 1,6-hexanediol oleate, 0.4 g of 30% hydrogen peroxide solution, 0.09 g of formic acid, and 6 mg of concentrated sulfuric acid were mixed and stirred at 58 °C for 8 h. The mixture was washed with deionized water until neutral and then rotary evaporated to obtain epoxy 1,6-hexanediol oleate.

[0044] 2) Under a nitrogen atmosphere, 0.8 g of epoxy 1,6-hexanediol oleate, 0.5 g of fluorinated diamine compound and 20 mL of dimethyl sulfoxide were mixed, heated to 100 °C and kept at that temperature for 5 h, cooled, washed and dried to obtain oleic acid derivative.

[0045] The preparation of the fluorinated diamine compound includes the following steps:

[0046] Under a nitrogen atmosphere, 0.05 mol of p-trifluoromethylbenzaldehyde and 0.35 mol of 2,6-dimethylaniline were mixed and heated to 78 °C. 2 mL of 37% hydrochloric acid solution was added, and the mixture was heated to 148 °C and kept at that temperature for 24 h. After cooling, 12.5 mL of 10% sodium hydroxide solution was added, and the mixture was extracted three times with 10 mL of dichloromethane. The mixture was then washed three times with deionized water and saturated sodium chloride solution, respectively. The mixture was rotary evaporated, and the precipitate was poured into methanol. After filtration, washing, and drying, a fluorinated diamine compound was obtained.

[0047] Example 2: A preparation process of a rubber sealing material for security lenses, comprising the following steps: putting composite EPDM rubber into a mixer, then adding modified graphene oxide, activator, and plasticizer in sequence, mixing, discharging the rubber, transferring it to a two-roll mill, adding vulcanizing agent and accelerator, filtering, settling, and vulcanizing to obtain a rubber sealing material for security lenses;

[0048] The raw material composition of the sealing material, by weight, is as follows: 80 parts of composite EPDM rubber, 20 parts of silicone, 3 parts of activator, 16 parts of modified graphene oxide, 29 parts of plasticizer, 2 parts of accelerator, and 2 parts of vulcanizing agent; the silicone is obtained by compounding fumed silica and precipitated silica in a mass ratio of 1:1.

[0049] The activator is a compound of zinc oxide, stearic acid, and itaconic acid in a mass ratio of 4:1:1.

[0050] The accelerator is 2-mercaptobenzothiazole;

[0051] The composite EPDM rubber is obtained by blending EPDM rubber and epoxidized EPDM rubber in a mass ratio of 1:1.

[0052] The preparation of the epoxidized EPDM rubber includes the following steps:

[0053] Under a nitrogen atmosphere, 30g of EPDM rubber and 500mL of n-hexane were mixed and kept at 50℃ in a water bath for 12min. 0.6g of formic acid and 1.5g of Tween 80 were added and stirred for 13min. 5.1g of hydrogen peroxide was added and kept at this temperature for 7.5h. The mixture was washed with sodium carbonate aqueous solution, separated, washed with deionized water until neutral, added to 1L of anhydrous ethanol, and dried under vacuum to obtain epoxidized EPDM rubber.

[0054] The preparation of the modified graphene oxide includes the following steps:

[0055] (1) Mix 0.2g of graphene oxide powder and 150mL of ultrapure water, sonicate for 9min, add 2g of alkali lignin and 50mL of ultrapure water, adjust the pH value to 10, centrifuge, vacuum filter and dry to obtain composite graphene oxide.

[0056] (2) Mix 0.2g of composite graphene oxide and 100mL of N,N-dimethylformamide, disperse by ultrasonication, add 37.6g of potassium fluoride and 5g of potassium iodide, stir for 13min, add 20mL of epichlorohydrin, heat to 100℃ and keep warm for 14.5h, centrifuge, wash and freeze dry to obtain epoxidized composite graphene oxide;

[0057] (3) Under a nitrogen atmosphere, 5.3g of epoxidized composite graphene oxide, 2.2g of fluorinated diamine compound and 100mL of dimethyl sulfoxide were mixed, heated to 108℃ and kept at that temperature for 3.5h, cooled, washed and dried to obtain modified graphene oxide.

[0058] The plasticizer is an oleic acid derivative, and its preparation includes the following steps:

[0059] 1) Under a nitrogen atmosphere, 2.1 g of oleic acid and 5.9 g of 1,6-hexanediol were mixed, and 0.03 g of concentrated sulfuric acid was added. The mixture was heated to 130 °C and kept at that temperature for 7.5 h. The solution was washed with sodium bicarbonate until neutral, washed with water, and allowed to stand to obtain 1,6-hexanediol oleate. 0.6 g of 1,6-hexanediol oleate, 0.4 g of 30% hydrogen peroxide solution, 0.09 g of formic acid, and 6 mg of concentrated sulfuric acid were mixed and stirred at 60 °C for 7.5 h. The mixture was washed with deionized water until neutral and then rotary evaporated to obtain epoxy 1,6-hexanediol oleate.

[0060] 2) Under a nitrogen atmosphere, 0.8 g of epoxy 1,6-hexanediol oleate, 0.5 g of fluorinated diamine compound and 20 mL of dimethyl sulfoxide were mixed, heated to 103 °C and kept at that temperature for 4.5 h, cooled, washed and dried to obtain oleic acid derivative.

[0061] The preparation of the fluorinated diamine compound includes the following steps:

[0062] Under a nitrogen atmosphere, 0.05 mol of p-trifluoromethylbenzaldehyde and 0.35 mol of 2,6-dimethylaniline were mixed, heated to 80 °C, and 2 mL of 37% hydrochloric acid solution was added. The mixture was then heated to 150 °C and kept at that temperature for 23.5 h. After cooling, 12.5 mL of 10% sodium hydroxide solution was added, and the mixture was extracted four times with 10 mL of dichloromethane. The mixture was then washed four times with deionized water and saturated sodium chloride solution, and the solution was rotary evaporated. The precipitate was then poured into methanol, filtered, washed, and dried to obtain a fluorinated diamine compound.

[0063] Example 3: A preparation process of a rubber sealing material for security lenses, comprising the following steps: EPDM composite rubber is put into a mixer, then modified graphene oxide, activator, and plasticizer are added in sequence, mixed, discharged, transferred to a two-roll mill, vulcanizing agent and accelerator are added, filtered, allowed to stand, and vulcanized to obtain a rubber sealing material for security lenses;

[0064] The sealing material, by weight, comprises: 80 parts of composite EPDM rubber, 20 parts of silicone, 5 parts of activator, 18 parts of modified graphene oxide, 35 parts of plasticizer, 3 parts of accelerator, and 3 parts of vulcanizing agent; the silicone is obtained by compounding fumed silica and precipitated silica in a mass ratio of 1:1.

[0065] The activator is a compound of zinc oxide, stearic acid, and itaconic acid in a mass ratio of 4:1:1.

[0066] The accelerator is 2-mercaptobenzothiazole;

[0067] The composite EPDM rubber is obtained by blending EPDM rubber and epoxidized EPDM rubber in a mass ratio of 1:1.

[0068] The preparation of the epoxidized EPDM rubber includes the following steps:

[0069] Under a nitrogen atmosphere, 30g of EPDM rubber and 500mL of n-hexane were mixed and kept at 52℃ in a water bath for 10min. 0.6g of formic acid and 1.5g of Tween 80 were added and stirred for 15min. 5.1g of hydrogen peroxide was added and kept at this temperature for 8h. The mixture was washed with sodium carbonate aqueous solution, separated, washed with deionized water until neutral, added to 1L of anhydrous ethanol, and dried under vacuum to obtain epoxidized EPDM rubber.

[0070] The preparation of the modified graphene oxide includes the following steps:

[0071] (1) Mix 0.2g of graphene oxide powder and 150mL of ultrapure water, sonicate for 10min, add 2g of alkali lignin and 50mL of ultrapure water, adjust the pH value to 10.1, centrifuge, vacuum filter and dry to obtain composite graphene oxide.

[0072] (2) Mix 0.2g of composite graphene oxide and 100mL of N,N-dimethylformamide, disperse by ultrasonication, add 37.6g of potassium fluoride and 5g of potassium iodide, stir for 15min, add 20mL of epichlorohydrin, heat to 102℃ and keep warm for 14h, centrifuge, wash and freeze dry to obtain epoxidized composite graphene oxide.

[0073] (3) Under a nitrogen atmosphere, 5.3g of epoxidized composite graphene oxide, 2.2g of fluorinated diamine compound and 100mL of dimethyl sulfoxide were mixed, heated to 110℃ and kept at that temperature for 3h, cooled, washed and dried to obtain modified graphene oxide.

[0074] The plasticizer is an oleic acid derivative, and its preparation includes the following steps:

[0075] 1) Under a nitrogen atmosphere, 2.1 g of oleic acid and 5.9 g of 1,6-hexanediol were mixed, and 0.03 g of concentrated sulfuric acid was added. The mixture was heated to 132 °C and kept at that temperature for 7 h. The solution was washed with sodium bicarbonate until neutral, washed with water, and allowed to stand to obtain 1,6-hexanediol oleate. 0.6 g of 1,6-hexanediol oleate, 0.4 g of 30% hydrogen peroxide solution, 0.09 g of formic acid, and 6 mg of concentrated sulfuric acid were mixed and stirred at 62 °C for 7 h. The mixture was washed with deionized water until neutral and then rotary evaporated to obtain epoxy 1,6-hexanediol oleate.

[0076] 2) Under a nitrogen atmosphere, 0.8 g of epoxy 1,6-hexanediol oleate, 0.5 g of fluorinated diamine compound and 20 mL of dimethyl sulfoxide were mixed, heated to 105 °C and kept at that temperature for 4 h, cooled, washed and dried to obtain oleic acid derivative.

[0077] The preparation of the fluorinated diamine compound includes the following steps:

[0078] Under a nitrogen atmosphere, 0.05 mol of p-trifluoromethylbenzaldehyde and 0.35 mol of 2,6-dimethylaniline were mixed and heated to 82 °C. 2 mL of 37% hydrochloric acid solution was added, and the mixture was heated to 152 °C and kept at that temperature for 23 h. After cooling, 12.5 mL of 10% sodium hydroxide solution was added, and the mixture was extracted five times with 10 mL of dichloromethane. The mixture was then washed five times with deionized water and saturated sodium chloride solution, rotary evaporated, and the precipitate was poured into methanol. The precipitate was filtered, washed, and dried to obtain a fluorinated diamine compound.

[0079] Comparative Example 1: Using Example 3 as the control group, the modified graphene oxide was replaced with graphene oxide, and other processes were normal.

[0080] Comparative Example 2: Using Example 3 as the control group, dioctyl phthalate (D109648: Aladdin reagent) was used to replace the oleic acid derivative, and other processes were normal.

[0081] Comparative Example 3: Using Example 3 as the control group, no epoxidized EPDM rubber was prepared, and other processes were normal.

[0082] In the examples and comparative examples, the vulcanization working conditions were: temperature 175°C and time 240s.

[0083] Source of raw materials used (for illustrative purposes only):

[0084] EPDM rubber 5467C: Alangxin Technology; Fumed silica gel TY171-70, precipitated silica gel TY371-70: Xin'an Tianyu Organosilicon Co., Ltd.; Vulcanizing agent C-14: Dawei Technology; Alkali lignin 471003: Sigma-Aldrich (Shanghai) Trading Co., Ltd.; Zinc oxide Z111836, Stearic acid S754992, Itaconic acid I106140, 2-Mercaptobenzothiazole M104864, Tween 80 T434510, Graphene oxide powder G139803, N, N-Dimethylformamide D111999, epichlorohydrin E108182, dimethyl sulfoxide D103274, oleic acid O108484, 1,6-hexanediol H103708, p-trifluoromethylbenzaldehyde T106647, 2,6-dimethylaniline D105633: Aladdin reagent; hydrochloric acid, sodium hydroxide, dichloromethane, sodium chloride, methanol, n-hexane, formic acid, sodium carbonate, ethanol, potassium fluoride, potassium iodide, hydrogen peroxide, formic acid, concentrated sulfuric acid, sodium bicarbonate, analytical grade: Sinopharm Group reagent.

[0085] Performance testing: The sealing materials prepared in the examples and comparative examples were tested.

[0086] Water absorption test: Place a 5g sample in a constant temperature and humidity chamber (temperature 55℃, humidity 93%) and calculate the water absorption rate of the sample after 96h.

[0087] Compression test: The sample is kept at 140℃ for 2 hours, and then placed in a compression deformation device (compression amount of 33.3%). The compression deformation device is kept at 105℃ for 96 hours. After removal, the sample is placed for 30 minutes to test its dimensions. Compression deformation = (h1-h2) / (h1-hs), where h1 is the initial sample height, h2 is the sample height after the test, and hs is the limiter height, which is 0.94cm. Compression deformation less than or equal to 30% is considered qualified; otherwise, it is considered unqualified.

[0088] Oil leakage test: Place the oil-absorbing paper and the sample into the compression deformation device (compression amount of 40%), keep the compression deformation device at 105℃ for 3 hours, and then take out the sample to observe whether there is oil on the oil-absorbing paper. If there is no oil, it is qualified; otherwise, it is unqualified. The results are shown in Table 1.

[0089] Table 1

[0090] Water absorption rate (%) Compression test Oil leakage test Example 1 0.092 qualified qualified Example 2 0.091 qualified qualified Example 3 0.090 qualified qualified Comparative Example 1 0.123 Unqualified Unqualified Comparative Example 2 0.135 Unqualified Unqualified Comparative Example 3 0.126 Unqualified Unqualified

[0091] This invention provides a rubber sealing material for security cameras and its preparation process. By optimizing the composition and process design, a sealing material with good sealing performance, excellent water resistance, high temperature resistance, and aging resistance is prepared, which meets the requirements of security cameras for sealing materials.

[0092] Comparing Example 3 with Comparative Example 1, it can be seen that by using graphene oxide as a reinforcing agent and lignin as an antioxidant, alkali lignin nanoparticles were prepared using alkali lignin as a raw material, and then co-assembled with graphene oxide to prepare composite graphene oxide. In order to improve the uniformity of the dispersion of composite graphene oxide in the rubber matrix, the composite graphene oxide was modified. First, it was epoxidized with epichlorohydrin, and then a fluorinated diamine compound was grafted using the epoxy=amino reaction. The fluorinated diamine compound was prepared from p-trifluoromethylbenzaldehyde and 2,6-dimethylaniline. The introduction of fluorine element improved its water resistance and thermal stability. At the same time, the introduction of multiple active sites on the modified graphene oxide helped to improve its interfacial compatibility with the rubber matrix, so that graphene oxide and lignin were firmly attached to the sealing material, improving its durability.

[0093] Comparing Example 3 with Comparative Example 2, it can be seen that most current chemical plasticizers have problems such as high cost, poor migration resistance, and environmental unfriendliness. In this invention, environmentally friendly materials oleic acid and 1,6-hexanediol are used as raw materials. First, esterification is carried out to obtain the plasticizer 1,6-hexanediol oleate, then epoxidation is performed, and then fluorinated diamine compounds are grafted using an epoxy-amine reaction to generate oleic acid derivatives with good water resistance and high thermal stability as plasticizers, thereby significantly improving the various performances of the sealing components.

[0094] Comparing Example 3 with Comparative Example 3, it can be seen that in order to reduce the amount of vulcanizing agent used in this invention, epoxidized EPDM rubber is first synthesized through in-situ epoxidation with formic acid-hydrogen peroxide as the raw material for EPDM rubber. Based on the reaction of epoxy with amino and carboxyl groups, a cross-linked network structure containing ester bonds is constructed with activator, modified graphene oxide and plasticizer. At the same time, the addition of zinc oxide in the activator can activate the epoxy groups, effectively improve its cross-linking efficiency and cross-linking density, thereby improving the various performances of the sealing component.

[0095] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention's specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A rubber sealing material for security cameras, characterized in that, The sealing material, by weight, comprises: 80 parts of composite EPDM rubber, 20 parts of silicone rubber, 2-5 parts of activator, 12-18 parts of modified graphene oxide, 20-35 parts of plasticizer, 1-3 parts of accelerator, and 1-3 parts of vulcanizing agent; the silicone rubber is obtained by compounding fumed silica and precipitated silica in a mass ratio of 1:

1. The composite EPDM rubber is obtained by blending EPDM rubber and epoxidized EPDM rubber in a mass ratio of 1:

1. The plasticizer is an oleic acid derivative; The preparation of the oleic acid derivative includes the following steps: 1) Under a nitrogen atmosphere, oleic acid and 1,6-hexanediol are mixed, concentrated sulfuric acid is added, the temperature is raised to 128-132℃ and kept at this temperature for 7-8 hours. The solution is washed with sodium bicarbonate until neutral, washed with water, and allowed to stand to obtain 1,6-hexanediol oleate. 1,6-hexanediol oleate, hydrogen peroxide solution, formic acid, and concentrated sulfuric acid are mixed and stirred at 58-62℃ for 7-8 hours. The solution is washed with deionized water until neutral and then rotary evaporated to obtain epoxy 1,6-hexanediol oleate. 2) Under a nitrogen atmosphere, epoxy 1,6-hexanediol oleate, fluorinated diamine compound and dimethyl sulfoxide are mixed, heated to 100-105℃ and kept at the temperature for 4-5 hours, cooled, washed and dried to obtain oleic acid derivative. The preparation of the modified graphene oxide includes the following steps: (1) Mix graphene oxide powder and ultrapure water, sonicate for 8-10 min, add alkali lignin and ultrapure water mixture, adjust pH to 9.9-10.1, centrifuge, vacuum filter and dry to obtain composite graphene oxide. (2) Mix the composite graphene oxide and N,N-dimethylformamide, disperse by ultrasonication, add potassium fluoride and potassium iodide, stir for 10-15 min, add epichlorohydrin, heat to 98-102℃ and keep warm for 14-15 h, centrifuge, wash and freeze dry to obtain epoxidized composite graphene oxide. (3) Under a nitrogen atmosphere, epoxidized composite graphene oxide, fluorinated diamine compound and dimethyl sulfoxide are mixed, heated to 105-110℃ and kept at the temperature for 3-4 hours, cooled, washed and dried to obtain modified graphene oxide. The activator is a mixture of zinc oxide, stearic acid, and itaconic acid in a mass ratio of 4:1:

1.

2. The rubber sealing material for security lenses according to claim 1, characterized in that, The accelerator is one or more of 2-mercaptobenzothiazole, N,N'-diphenyl-thiourea, and N-cyclohexyl-2-benzothiazole sulfenamide.

3. The rubber sealing material for security lenses according to claim 1, characterized in that, The preparation of the epoxidized EPDM rubber includes the following steps: Under a nitrogen atmosphere, EPDM rubber and n-hexane are mixed and kept at a temperature of 48-52℃ in a water bath for 10-15 minutes. Formic acid and Tween 80 are added and stirred for 10-15 minutes. Hydrogen peroxide is added and kept at a temperature of 7-8 hours. The mixture is then washed with sodium carbonate aqueous solution, separated, washed with deionized water until neutral, added to anhydrous ethanol, and dried under vacuum to obtain epoxidized EPDM rubber.

4. The rubber sealing material for security lenses according to claim 1, characterized in that, The preparation of the fluorinated diamine compound includes the following steps: Under a nitrogen atmosphere, p-trifluoromethylbenzaldehyde and 2,6-dimethylaniline were mixed and heated to 78-82°C. Hydrochloric acid solution was added, and the temperature was raised to 148-152°C and maintained for 23-24 hours. After cooling, sodium hydroxide solution was added, and the mixture was extracted 3-5 times with dichloromethane. The mixture was then washed 3-5 times with deionized water and saturated sodium chloride solution, rotary evaporated, and the precipitate was poured into methanol. The precipitate was filtered, washed, and dried to obtain a fluorinated diamine compound.

5. The manufacturing process of a rubber sealing material for a security lens according to any one of claims 1-4, characterized in that, Includes the following steps: Composite EPDM rubber and silicone are put into a mixer, and then modified graphene oxide, activator and plasticizer are added in sequence. After mixing, the rubber is discharged and transferred to a two-roll mill. A vulcanizing agent and accelerator are added, and the mixture is filtered, allowed to stand and vulcanized to obtain a rubber sealing material for security lenses.