A rubber sealing ring fitting for a coffee pot

Abstract

The present invention discloses a rubber sealing ring fitting for a coffee pot. The rubber sealing ring fitting, by weight parts, comprises the following components: 95-105 parts of silicone rubber raw rubber, 38-43 parts of fumed silica, 5-8 parts of hydroxy silicone oil, 1-3 parts of hyperbranched crosslinking agent, 0.1-0.14 parts of Kast catalyst, 0.05-0.07 parts of inhibitor, and 1.0-1.2 parts of vulcanizing agent; the hyperbranched crosslinking agent and the vulcanizing agent are used to crosslink the silicone rubber, which can form a uniform three-dimensional crosslinked network, and the obtained rubber sealing ring has excellent anti-aging ability and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a rubber sealing ring fitting for a coffee pot. Background Art

[0002] Rubber sealing rings have various configurations. Among them, the O-ring has a simple overall structure and low cost, and is widely used in various equipment. Silicone rubber has excellent chemical stability, weather resistance, electrical insulation, hydrophobic recovery, and physiological inertness, and has a wide range of applications in the fields of aerospace, telecommunications, food and beverage, and medical treatment. However, due to the structural characteristics of the molecular chain of the rubber material itself and the influence of external environmental factors such as temperature, humidity, and oxygen during storage, the rubber sealing ring is extremely prone to aging. As time goes by, the aging degree of the rubber sealing ring accumulates continuously, resulting in a decrease in its elasticity and sealing performance.

[0003] The high-temperature resistance of silicone rubber is greatly related to factors such as the structure of the rubber molecular chain, the content of water and impurities, and the use environment. The methods to improve the high-temperature resistance of silicone rubber are as follows: (1) Modifying the polymer molecular structure, which can be divided into main-chain modification and side-chain modification; (2) Using a suitable cross-linking agent to improve the stability of the cross-linking bonds; (3) Using high-temperature resistant additives. The stability of the cross-linking bonds between the molecular chains of silicone rubber has a great influence on the high-temperature resistance of the product. The better the thermal stability of the cross-linking bonds, the better the high-temperature resistance of the rubber, thereby improving the anti-aging ability of the rubber sealing ring against aging. Summary of the Invention

[0004] Based on this, the present invention provides a rubber sealing ring fitting for a coffee pot and its preparation method. By using a hyperbranched cross-linking agent and a vulcanizing agent to cross-link silicone rubber, a uniform three-dimensional cross-linked network can be formed, and the obtained rubber sealing ring has excellent anti-aging ability and mechanical properties.

[0005] The technical solution to achieve the object of the present invention is as follows:

[0006] A rubber sealing ring fitting for a coffee pot, the rubber sealing ring fitting, by weight, comprises the following components: 95 - 105 parts of silicone rubber raw rubber, 38 - 43 parts of fumed silica, 5 - 8 parts of hydroxyl silicone oil, 1 - 3 parts of hyperbranched cross-linking agent, 0.1 - 0.14 parts of Kast catalyst, 0.05 - 0.07 parts of inhibitor, 1.0 - 1.2 parts of vulcanizing agent; the preparation method of the hyperbranched cross-linking agent is as follows:

[0007] S1. Add 1 eq of N,N'-methylenebisacrylamide to a reaction kettle containing methanol and water, stir at a temperature of 30 - 35 °C until completely dissolved, then add 1.05 - 1.1 eq of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and stir at 55 - 65 °C for 22 - 24 h;

[0008] S2. Add 2.0 - 2.1 eq of the modified methacrylate monomer to the mixed solution in step S1, stir at 55 - 65 °C for 22 - 24 h, then remove the solvent by rotary evaporation. The obtained solid is washed successively with deionized water and a mixed solution of petroleum ether and ethyl acetate to obtain the hyperbranched crosslinking agent;

[0009] The modified methacrylate monomer has the molecular structure of formula I as follows:

[0010]

[0011] Preferably, the raw silicone rubber is methyl vinyl silicone rubber, and the vinyl content of the methyl vinyl silicone rubber is 0.05% - 0.24%.

[0012] More preferably, the methyl vinyl silicone rubber is at least one of the vinyl content of 0.05% and the vinyl content of 0.24%.

[0013] Preferably, the inhibitor is one or several of 1-ethynylcyclohexanol, diallyl maleate, and diethyl fumarate; the vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0014] More preferably, the inhibitor is 1-ethynylcyclohexanol.

[0015] Preferably, the volume ratio of methanol to water in step S1 is 3:1 - 2.

[0016] Preferably, the preparation method of the modified methacrylate monomer is as follows:

[0017] 1) Place 1 eq of hexamethylcyclotrisiloxane in a round-bottom flask. Under an argon atmosphere, add 1 eq of dimethylchlorosilane and 20 - 30 eq of acetonitrile, and then add a catalytic amount of dimethylformamide. After stirring the mixture at room temperature for 60 - 70 h, the reaction mixture is directly purified by vacuum distillation, and the fraction at 39 - 41 °C is collected under 1.1 mbar;

[0018] 2) Under a nitrogen atmosphere, at a temperature of 0 - 5 °C, dissolve 2.0 - 2.5 eq of 2-hydroxyethyl methacrylate and 2.5 - 3.0 eq of triethylamine in dry dichloromethane and add it to the reaction kettle. Disperse 1 eq of the fraction obtained in step 1) in dry dichloromethane and slowly add it dropwise to the reaction kettle. Stir for 20 - 30 min, raise the temperature to room temperature and stir for 4 - 5 h. Remove the solvent and purify by column chromatography to obtain the modified methacrylate monomer.

[0019] More preferably, the dimethylformamide in step 1) is 1% of the mass of hexamethylcyclotrisiloxane.

[0020] Preferably, the method for preparing the rubber seal ring fitting is as follows:

[0021] (1) Pour fumed silica into a vacuum kneader, then slowly add silicone rubber raw rubber. After closing the air extraction valve and exhaust valve of the kneader, carry out mixing. During the mixing process, add hydroxyl silicone oil, hyperbranched crosslinking agent and inhibitor in batches. After the filler and raw rubber are mixed evenly, heat the kneader to 150 °C and mix for 2 h, then carry out vacuum mixing at 120 °C for 1 h. After cooling to room temperature, obtain the silicone rubber masterbatch.

[0022] (2) Add the Kast catalyst and vulcanizing agent to the masterbatch with a two-roll mill, mix evenly and take out the sheet. Then put it into a mold and vulcanize it at 165 °C and 8 MPa for 18 - 20 min in a flat vulcanizer. After trimming and cleaning, obtain the rubber seal ring fitting.

[0023] Beneficial effects

[0024] The present invention has the following beneficial effects: providing a rubber seal ring with excellent anti-aging ability and mechanical properties. Crosslinking silicone rubber with a hyperbranched crosslinking agent and a vulcanizing agent can form a uniform three-dimensional crosslinked network; the amide groups in the molecule can act as antioxidant stabilizers. The multiple crosslinked structures limit the penetration of oxygen and provide long-term stability of mechanical strength. The complex spatial structure slows down the diffusion rate of water molecules; the diversity of crosslinking points provides structural redundancy, and the overall performance can be maintained even if partial degradation occurs. Description of the drawings

[0025] Figure 1 It is the synthesis step of the modified methacrylate monomer of the present invention;

[0026] Figure 2 It is the synthesis step and schematic diagram of the hyperbranched crosslinking agent of the present invention;

[0027] Figure 3 It is the comparison chart of the nuclear magnetic hydrogen spectrum of the modified methacrylate monomer and the hyperbranched crosslinking agent of the present invention.

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0030] The raw materials and equipment used in the embodiments and comparative examples are described as follows:

[0031] Vacuum kneading machine: Model SH-5, Jiangsu Rugao Shengteng Kneading Machinery Co., Ltd.;

[0032] Double-roll mixing mill: Model XSK1608, Dongfang Machinery, Huzhou, Zhejiang;

[0033] Flat vulcanizing press: Model XLB-D400×400, Dongfang Machinery, Huzhou, Zhejiang;

[0034] Methyl vinyl silicone rubber (MVQ110-0): vinyl content of 0.03-0.06%, purchased from Hesheng Silicon Industry Co., Ltd.;

[0035] Methyl vinyl silicone rubber (MVQ110-3): vinyl content of 0.19-0.24%, purchased from Hesheng Silicon Industry Co., Ltd.;

[0036] Fumed silica: brand HP-200, purchased from Jiangxi Hongbai New Materials Co., Ltd.;

[0037] Hydroxyl silicone oil: hydroxyl content 8wt.%, purchased from Wuhan Jiyesheng Chemical Co., Ltd.;

[0038] Hydrogenated silicone oil: hydrogen content 1.2wt.%, Shenzhen Senri Silicone Materials Co., Ltd.;

[0039] Custer catalyst: Pt content 2%, purchased from Shanghai MacLean Biochemical Technology;

[0040] Inhibitor: 1-ethynylcyclohexanol, No. E809391, purchased from Shanghai MacLean Biochemical Technology;

[0041] Curing agent: 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane, No. T819468, purchased from Shanghai MacLean Biochemical Technology;

[0042] N,N'-Methylenebisacrylamide: No. 1084860, purchased from Shanghai Haohong Biopharmaceutical Technology Co., Ltd.;

[0043] 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane: Beijing Huawei Ruike Chemical Technology Co., Ltd.;

[0044] Hexamethylcyclotrisiloxane: No. H830620, purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0045] Dimethylchlorosilane: No. M01395, purchased from Shanghai Merck Chemical Technology Co., Ltd.;

[0046] 2-Hydroxyethyl methacrylate: No. H810855, purchased from Shanghai Macklin Biochemical Co., Ltd.;

[0047] Modified methacrylate monomer (self-made):

[0048] 1) Place 1 eq of hexamethylcyclotrisiloxane in a round-bottom flask. Under an argon atmosphere, add 1 eq of dimethylchlorosilane and 30 eq of acetonitrile, and then add a catalytic amount of dimethylformamide. After the mixture is stirred at room temperature for 65 h, the reaction mixture is directly purified by vacuum distillation, and the fraction at 39 - 41 °C is collected under 1.1 mbar;

[0049] 2) Under a nitrogen atmosphere, at a temperature of 0 - 5 °C, dissolve 2.5 eq of 2-hydroxyethyl methacrylate and 3.0 eq of triethylamine in dry dichloromethane and add them to the reaction kettle. Dissolve 1 eq of the fraction obtained in step 1) in dry dichloromethane and slowly add it dropwise to the reaction kettle. Stir for 30 min, raise the temperature to room temperature and stir for 5 h. Remove the solvent and purify by column chromatography to obtain the modified methacrylate monomer.

[0050] Hyperbranched crosslinker (self-made)

[0051] S1. Add 1 eq of N,N'-methylenebisacrylamide to a reaction kettle containing methanol and water. Stir at 35 °C until completely dissolved, and then add 1.1 eq of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. Stir at 60 °C for 24 h;

[0052] S2. Add 2.05 eq of the modified methacrylate monomer to the mixed solution in step S1. After stirring at 60 °C for 24 h, remove the solvent by rotary evaporation. The obtained solid is washed successively with deionized water, and a mixed solution of petroleum ether and ethyl acetate to obtain the hyperbranched crosslinker.

[0053] As Figure 3 From the comparison chart of the 1H NMR spectra of the modified methacrylate monomer and the hyperbranched crosslinker, it can be seen that the double bond peaks at chemical shifts of 5.5 ppm and 6.0 ppm disappear after polymerization, indicating that Michael addition occurs between the amino group and the double bond.

[0054] A rubber sealing ring fitting for a coffee pot, and the preparation method is as follows:

[0055] (1) Pour fumed silica into a vacuum kneader, and then slowly add MVQ110-0 and MVQ110-3. After closing the air extraction valve and exhaust valve of the kneader, carry out mixing. During the mixing process, add hydroxyl silicone oil, hyperbranched crosslinking agent and inhibitor in batches. After the filler and raw rubber are mixed evenly, heat the kneader to 150 °C and mix for 2 h, then carry out vacuum mixing at 120 °C for 1 h. After cooling to room temperature, a silicone rubber masterbatch is obtained;

[0056] (2) Add a Caster catalyst and a vulcanizing agent to the masterbatch with a two-roll mill. After mixing evenly, take out the sheet, then put it into a mold, and vulcanize it at 165 °C and 8 MPa in a flat vulcanizer for 18-20 min. After trimming and cleaning, a rubber sealing ring fitting is obtained.

[0057] Table 1 Rubber sealing ring fitting formula (parts)

[0058]

[0059] The following is the test method for the performance parameters involved in the present invention:

[0060] (1) Crosslinking density determination: The crosslinking density is measured by the equilibrium swelling method using toluene as a solvent; the vulcanized rubber is cut into a sample strip of 10 mm×10 mm×2 mm and placed in a blast drying oven at 80 °C for 24 h to remove moisture and other volatile components in the sample. After the sample strip is cooled to room temperature, accurately measure the original mass (m0) of the sample strip, and then soak the sample strip in toluene at room temperature, continuously record the mass of the sample strip until the sample strip reaches swelling equilibrium and measure the mass of the swollen sample strip (m s ), the volume fraction of the swollen rubber is calculated according to Equation 1; the crosslinking density (V e ) is calculated according to Equation 2;

[0061]

[0062] In Equation 1, m0 is the original mass of the sample strip; m s is the mass of the swollen sample strip; ρ is the density of the sample strip; ρ t is the density of toluene; in Equation 2, V0 is the molar volume of toluene, V0 = 106.54×10 -3 , χ is the interaction parameter between toluene and rubber,

[0063] (2) Mechanical property tests: Tensile and tear properties were tested on a tensile testing machine, and the test standards were executed in accordance with ISO 37-2005 and ISO 34-1-2004 standards respectively. Shore A hardness was tested on a Shore rubber hardness tester, and the test standard was executed in accordance with ISO 7619-1-2004 standard;

[0064] (3) Hydrophobic recovery test: The rubber was cut into circular pieces with a diameter of 25 mm and a thickness of 2 mm and then placed in a plasma instrument for 30 s to transform the rubber surface into a completely hydrophilic surface; then, the circular pieces were placed in an environment of 25 °C, and a contact angle measuring instrument was used to continuously record the change of the water contact angle on the rubber surface until the hydrophobicity of the surface no longer changed significantly;

[0065] (5) Compression set: Cylindrical rubber specimens with a height of about 10 cm (±0.3) mm were prepared in accordance with GB / T 1683-2018 "Determination Method for Compression Set of Vulcanized Rubber at Constant Deformation". The rubber sample was installed in the fixture with a compression amount of 30%. The test conditions were a temperature of 90 °C and a humidity of 90%. After each selected interval, the rubber sample was taken out and the load was removed. After standing at room temperature for one hour, the height was measured and the measurement data was recorded.

[0066] Table 2 Crosslinking density, mechanical properties and hydrophobic recovery ability of rubber seal ring fittings

[0067]

[0068] Table 3 Compression set of rubber seal ring fittings

[0069]

[0070] From the data of Examples 3-7 in Table 2, it can be seen that as the content of the hyperbranched crosslinking agent increases, the crosslinking density, hardness, and 100% modulus of the obtained materials gradually increase; the tensile strength, elongation at break, and tear strength first increase and then decrease; the hydrophobic recovery initially changes little and then suddenly decreases as it increases. As the crosslinking density increases, the migration ability of small molecule siloxane or polysiloxane molecular chains inside the silicone rubber gradually decreases, resulting in a decrease in the hydrophobic recovery ability. From the data of Comparative Examples 2 and 3, it can be seen that without adding the hyperbranched crosslinking agent prepared in the present invention or replacing it with linear hydrogen-containing silicone oil, the rubber properties prepared are inferior to those of the rubber prepared in Examples 3-7 except for hydrophobic recovery and elongation at break; from the data of Comparative Example 1, it can be seen that adding too much hyperbranched crosslinking agent of the present invention will result in too high hardness, which is not conducive to being used as a sealing fitting.

[0071] Since the rubber seal ring fittings of the coffee pot are in a humid and hot environment for a long time, therefore, we mainly tested the compression set under humid and hot environment;

[0072] As can be seen from the data in Table 3, in the test environment with a temperature of 90°C and a humidity of 90%, it can be seen that as the crosslinking density increases, the compression set rate gradually decreases, but the improvement effect becomes less and less obvious. Among them, the mechanical properties and hydrophobic recovery ability of Example 5 are relatively excellent, and the compression set rate only changes by 0.18% in 192 hours, which is suitable for the use environment of the rubber seal ring fittings of the coffee pot.

[0073] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A rubber sealing ring fitting for a coffee pot, characterized in that, The rubber sealing ring fitting, by weight parts, comprises the following components: 95 - 105 parts of silicone rubber raw rubber, 38 - 43 parts of fumed silica, 5 - 8 parts of hydroxy silicone oil, 1 - 3 parts of hyperbranched crosslinking agent, 0.1 - 0.14 parts of Kaster catalyst, 0.05 - 0.07 parts of inhibitor, 1.0 - 1.2 parts of vulcanizing agent; The preparation method of the hyperbranched crosslinking agent is as follows: S1. Add 1eq of N,N'-methylenebisacrylamide into a reaction kettle filled with methanol and water, stir at 30 - 35°C until completely dissolved, then add 1.05 - 1.1eq of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and stir at 55 - 65°C for 22 - 24h; S2. Add 2.0 - 2.1eq of modified methacrylate monomer into the mixed solution of step S1, stir at 55 - 65°C for 22 - 24h, then remove the solvent by rotary evaporation. The obtained solid is washed successively with deionized water and a mixed solution of petroleum ether and ethyl acetate to obtain the hyperbranched crosslinking agent; The modified methacrylate monomer has the molecular structure of formula I as follows: The silicone rubber raw rubber is methyl vinyl silicone rubber, and the vinyl content of the methyl vinyl silicone rubber is 0.04% - 0.24%.

2. The rubber sealing ring fitting for a coffee pot according to claim 1, characterized in that, The inhibitor is one or more of 1-ethynylcyclohexanol, diallyl maleate and diethyl fumarate; The vulcanizing agent is 2,5-dimethyl-2,5-tert-butylperoxyhexane.

3. A rubber sealing ring fitting for a coffee pot as described in claim 1, characterized in that, In step S1, the volume ratio of methanol to water is 3:1 - 2:1; In step S2, the volume ratio of the mixed solution of petroleum ether and ethyl acetate is 10:1 - 5:

1.

4. The rubber sealing ring fitting for a coffee pot according to claim 1, characterized in that, The preparation method of the modified methacrylate monomer is as follows: 1) Place 1eq of hexamethylcyclotrisiloxane in a round-bottom flask. Under an argon atmosphere, add 1eq of dimethylchlorosilane and 20 - 30eq of acetonitrile, and then add a catalytic amount of dimethylformamide. The mixture is stirred at room temperature for 60 - 70h, and the reaction mixture is directly purified by vacuum distillation. The fraction at 39 - 41°C is collected under 1.1mbar; 2) Under a nitrogen atmosphere, at 0 - 5°C, dissolve 2.0 - 2.5eq of 2-hydroxyethyl methacrylate and 2.5 - 3.0eq of triethylamine in dry dichloromethane and add them into the reaction kettle. Dissolve 1eq of the fraction obtained in step 1) in dry dichloromethane and slowly add it dropwise into the reaction kettle, stir for 20 - 30min, warm up to room temperature and stir for 4 - 5h, remove the solvent, and purify by column chromatography to obtain the modified methacrylate monomer.

5. A rubber sealing ring fitting for a coffee pot according to claim 1, characterized in that, The preparation method of the rubber sealing ring fitting is as follows: (1) Pour fumed silica into a vacuum kneader, then slowly add silicone rubber raw rubber. After closing the air extraction valve and exhaust valve of the kneader, carry out mixing. During the mixing process, add hydroxy silicone oil, hyperbranched crosslinking agent and inhibitor in batches. After the filler and raw rubber are mixed evenly, heat the kneader to 150°C and mix for 2h, then carry out vacuum mixing at 120°C for 1h, and cool to room temperature to obtain silicone rubber masterbatch; (2) Add the Kast catalyst and vulcanizing agent to the masterbatch with a two-roll mill, take out the sheet after uniform mixing, then put it into a mold, and vulcanize it for 18 - 20 minutes under the conditions of 165 °C and 8 MPa in a flat vulcanizing machine. After trimming and cleaning, a rubber seal ring fitting is obtained.

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