Flame-retardant rubber waterstop for tunnel and preparation method of flame-retardant rubber waterstop

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a flame-retardant rubber waterstop for a tunnel and a preparation method of the flame-retardant rubber waterstop. The flame-retardant rubber waterstop for the tunnel is prepared by selecting the modified ethylene propylene rubber, the dopamine modified sepiolite and the modified magnesium oxide as main materials, the tensile strength is effectively improved, the tearing strength is increased, and good flame retardance is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a flame-retardant rubber waterstop for tunnels and a preparation method thereof. Background Art

[0002] In recent years, the shield tunnels that have developed rapidly adopt a precast segmental lining structure. A large number of longitudinal and circumferential joints make tunnel leakage almost ubiquitous. The frequent occurrence of tunnel leakage problems will, at the least, have a great impact on the psychology of drivers and pedestrians, and at the most, pose a serious threat to the safety of the tunnel structure, triggering serious safety accidents. At the same time, once the leakage disease appears, it is very difficult to completely solve. A waterstop is a shaped waterproof sealing material for deformation joints and construction joints of underground buildings. The rubber waterstop makes full use of the high elasticity and compression deformation of rubber materials, can produce elastic deformation under various loads to play an effective fastening and sealing role, and prevent water leakage, seepage and vibration damping and buffering effects.

[0003] Chinese Patent (Publication No. CN117143402A) discloses a flame-retardant natural rubber waterstop and a preparation method thereof. The invention uses natural rubber as the matrix material of the flame-retardant rubber waterstop, and introduces a composite flame retardant of ammonium polyphosphate, melamine borate and zinc borate into the matrix. The three cooperate to flame retard, significantly improving the flame retardancy and mechanical properties of the natural rubber waterstop. At the same time, polymethyl methacrylate is also added and coated on the surface of the composite flame retardant, further improving the flame retardancy of the natural rubber waterstop and also improving the mechanical properties of the natural rubber waterstop. However, in the prior art, the flame-retardant rubber waterstop for tunnels still has problems such as low tensile strength, small tear strength, and poor flame retardancy, seriously affecting its actual use.

[0004] Therefore, how to functionally modify the main components of the rubber waterstop to prepare a flame-retardant rubber waterstop for tunnels, effectively improve the tensile strength, increase the tear strength, and obtain good flame retardancy has become the key direction to be overcome. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a flame-retardant rubber waterstop for tunnels and a preparation method thereof, aiming to solve the problems in the prior art that the flame-retardant rubber waterstop for tunnels still has low tensile strength, small tear strength, and poor flame retardancy.

[0006] The present invention uses modified ethylene propylene rubber, dopamine-modified sepiolite and modified magnesium oxide as the main materials to prepare a flame-retardant rubber waterstop for tunnels, effectively improving the tensile strength, increasing the tear strength, and obtaining good flame retardancy.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows: In the first aspect of the present invention, a flame-retardant rubber waterstop for tunnels is provided. By weight, it includes the following components: 56 - 60 parts of polyisobutylene, 40 - 44 parts of modified ethylene-propylene rubber, 22 - 26 parts of carbon black, 18 - 22 parts of sepiolite, 10 - 14 parts of magnesium oxide, 6 - 8 parts of plasticizer, 4 - 6 parts of zinc oxide, 3 - 5 parts of stearic acid, 2.2 - 2.4 parts of diisopropylbenzene peroxide, and 1.2 - 1.6 parts of 2-mercaptobenzimidazole. The preparation method of the modified ethylene-propylene rubber includes: by weight, mixing 30 - 40 parts of montmorillonite, 40 - 50 parts of methyltrichlorosilane, and 100 - 120 parts of absolute ethanol for stirring treatment, then adding 100 - 120 parts of tetrahydrofuran to disperse evenly, and further adding 10 - 16 parts of 4-hydroxyphthalic anhydride and 2 - 4 parts of sodium hydride for an anhydride reaction to obtain anhydride-modified montmorillonite; mixing 60 - 70 parts of ethylene-propylene rubber and 8 - 12 parts of the anhydride-modified montmorillonite for kneading treatment to obtain the modified ethylene-propylene rubber.

[0008] As a preferred technical solution of the present invention, the conditions of the stirring treatment include: the stirring speed is 100 - 120 rpm, the temperature is 30 - 40 °C, and the time is 12 - 16 h.

[0009] As a preferred technical solution of the present invention, the conditions of the anhydride reaction include: the reaction temperature is 26 - 30 °C, and the reaction time is 26 - 28 h.

[0010] As a preferred technical solution of the present invention, the conditions of the kneading treatment include: the kneading treatment temperature is 100 - 110 °C, and the kneading treatment time is 12 - 16 min.

[0011] The modified ethylene-propylene rubber contains anhydride-modified montmorillonite. After the anhydride treatment, the interlayer spacing of the montmorillonite platelets increases, and the molecular chains of the ethylene-propylene rubber are more likely to insert into the interlayer of the montmorillonite to form an intercalated structure, enhancing the interfacial bonding force between the montmorillonite and the rubber matrix; at the same time, the montmorillonite platelets as nano-scale fillers can effectively restrict the slippage of the rubber molecular chains, thereby improving the tensile strength of the material.

[0012] As a preferred technical solution of the present invention, the sepiolite is dopamine-modified sepiolite; the preparation method of the dopamine-modified sepiolite includes: by weight, dispersing 1 - 3 parts of sepiolite and 1 - 3 parts of dopamine in 400 - 500 parts of tris(hydroxymethyl)aminomethane for heating reaction, and after the reaction is completed, drying under vacuum and grinding to obtain dopamine-modified sepiolite.

[0013] As a preferred technical solution of the present invention, the conditions of the heating reaction include: pH is 8.2 - 8.6, the temperature is 70 - 80 °C, and the time is 20 - 24 h.

[0014] Dopamine in dopamine-modified sepiolite has strong adhesiveness and reactivity, and can form a polydopamine coating on the surface of sepiolite, thereby improving the interfacial bonding between sepiolite and the rubber matrix. A stronger interfacial bonding force is formed between the dopamine-modified sepiolite and the rubber matrix, which can more effectively transfer stress and dissipate energy when stressed, reduce local stress concentration, and improve the tear strength of the rubber waterstop.

[0015] As a preferred technical solution of the present invention, the magnesium oxide is modified magnesium oxide; the preparation method of the modified magnesium oxide includes: by weight, adding 10-20 parts of magnesium oxide and 2-6 parts of γ-glycidoxypropyltrimethoxysilane to 120-140 parts of absolute ethanol for coupling treatment to obtain modified magnesium oxide.

[0016] As a preferred technical solution of the present invention, the conditions of the coupling treatment include: first stirring for 2-4 h, then centrifuging at a speed of 7000-8000 r / min for 6-10 min, and vacuum drying the lower layer precipitate.

[0017] The modified magnesium oxide is treated with the silane coupling agent γ-glycidoxypropyltrimethoxysilane, which can avoid uneven distribution caused by agglomeration. The uniformly dispersed modified magnesium oxide can better decompose endothermically at high temperatures, reduce the surface temperature of the material, and release inert gases to dilute oxygen and combustible gases, thereby inhibiting combustion and improving the flame retardancy of the material.

[0018] As a preferred technical solution of the present invention, the plasticizer is selected from at least one of triphenyl phosphate, tricresyl phosphate, and tolyldiphenyl phosphate.

[0019] In the second aspect of the present invention, there is provided a preparation method of a flame-retardant rubber waterstop for tunnels as described in the first aspect, including the following steps: By weight, mix 56-60 parts of polyisobutylene, 40-44 parts of modified ethylene-propylene rubber, 22-26 parts of carbon black, 18-22 parts of sepiolite, 10-14 parts of magnesium oxide, 6-8 parts of plasticizer, 4-6 parts of zinc oxide, 3-5 parts of stearic acid, and 2.2-2.4 parts of dicumyl peroxide for 10-15 min, then add a vulcanizing agent and mix for 3-5 min, and then let stand for 12-24 h and vulcanize to obtain a flame-retardant rubber waterstop for tunnels.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The modified ethylene-propylene rubber of the present invention contains acid anhydride groups, which can undergo nucleophilic addition reactions with the dopamine of dopamine-modified sepiolite. The epoxy groups introduced by the silane coupling agent in the modified magnesium oxide can not only carry out ring-opening addition reactions with the acid anhydride groups, but also form new covalent bonds with dopamine (the amino group in dopamine acts as a nucleophile and preferentially attacks one carbon atom in the epoxy group, resulting in the opening of the epoxy ring and the formation of covalent bonds). Thus, a high-density interconnected structure is constructed in the rubber waterstop, increasing the degree of crosslinking between molecular chains, improving the anti-deformation ability of the material, and effectively enhancing the tensile strength and tear strength. At the same time, the layered structure of montmorillonite in the interconnected structure can form a physical barrier in the matrix, delaying the diffusion of heat and volatile decomposition products. The nitrogen element in dopamine-modified sepiolite can capture free radicals during combustion, interrupt the combustion chain reaction, slow down the combustion rate, and magnesium oxide absorbs a large amount of heat at high temperatures, reducing the surface temperature of the material and delaying the thermal decomposition and combustion processes. Through the combined action of montmorillonite-dopamine-magnesium oxide, the flame retardancy performance is improved.

[0021] (2) The modified ethylene-propylene rubber contains acid anhydride-treated montmorillonite. After acid anhydride treatment, the layer spacing of montmorillonite sheets increases, and the molecular chains of ethylene-propylene rubber are more likely to insert into the interlayers of montmorillonite, forming an intercalated structure, which enhances the interfacial bonding force between montmorillonite and the rubber matrix. At the same time, the montmorillonite sheets, as nano-scale fillers, can effectively restrict the slippage of rubber molecular chains, thereby improving the tensile strength of the material.

[0022] (3) Dopamine in dopamine-modified sepiolite has strong adhesion and reactivity, and can form a polydopamine coating on the surface of sepiolite, thereby improving the interfacial bonding between sepiolite and the rubber matrix. A stronger interfacial bonding force is formed between dopamine-modified sepiolite and the rubber matrix, which can more effectively transfer stress and dissipate energy when stressed, reduce local stress concentration, and improve the tear strength of the rubber waterstop.

[0023] (4) The modified magnesium oxide treated with the silane coupling agent γ-glycidoxypropyltrimethoxysilane can avoid uneven distribution caused by agglomeration, and the uniformly dispersed modified magnesium oxide can better decompose endothermically at high temperatures, reduce the surface temperature of the material, and release inert gases to dilute oxygen and combustible gases, thereby inhibiting combustion and improving the flame retardancy performance of the material. Specific Embodiments

[0024] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0025] The sources of some components in the examples and comparative examples are as follows: Polyisobutylene, product number P304882, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Ethylene propylene diene monomer, grade 3092PM, purchased from Shanghai Sinopec Mitsui Chemicals Co., Ltd.; Carbon black, product number C124422, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Sepiolite, CAS number 63800-37-3, purchased from Sinopharm Chemical Reagent Co., Ltd.; Magnesium oxide, CAS number 1309-48-4, purchased from Shanghai Macklin Biochemical Co., Ltd.; Triphenyl phosphate, CAS number 115-86-6, purchased from Sinopharm Chemical Reagent Co., Ltd.; Tricresyl phosphate, CAS number 1330-78-5, purchased from Sinopharm Chemical Reagent Co., Ltd.; Toluene diphenyl phosphate, CAS number 26444-49-5, purchased from Sinopharm Chemical Reagent Co., Ltd.; Zinc oxide, CAS number 1314-13-2, purchased from Shanghai Macklin Biochemical Co., Ltd.; Stearic acid, CAS number 57-11-4, purchased from Shanghai Macklin Biochemical Co., Ltd.; Dicumyl peroxide, CAS number 80-43-3, purchased from Sinopharm Chemical Reagent Co., Ltd.; 2-Mercaptobenzimidazole, CAS number 583-39-1, purchased from Shanghai Macklin Biochemical Co., Ltd.; Montmorillonite, product number M141491, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Absolute ethanol, CAS number 64-17-5, purchased from Sinopharm Chemical Reagent Co., Ltd.; Methyltrichlorosilane, CAS number 75-79-6, purchased from Shanghai Macklin Biochemical Co., Ltd.; Tetrahydrofuran, CAS number 109-99-9, purchased from Sinopharm Chemical Reagent Co., Ltd.; 4-Hydroxyphthalic anhydride, CAS number 27550-59-0, purchased from Zhende Chemical Technology (Shanghai) Co., Ltd.; Sodium hydride, CAS number 7646-69-7, purchased from Sinopharm Chemical Reagent Co., Ltd.; Dopamine, CAS number 51-61-6, purchased from Shanghai Macklin Biochemical Co., Ltd.; Tris(hydroxymethyl)aminomethane, CAS number 77-86-1, purchased from Shanghai Macklin Biochemical Co., Ltd.; γ-Glycidoxypropyltrimethoxysilane, CAS number 2530-83-8, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0026] Preparation of dopamine-modified sepiolite: By weight, 3 parts of sepiolite and 3 parts of dopamine are dispersed in 500 parts of tris(hydroxymethyl)aminomethane for heating reaction (pH = 8.6, temperature = 80 °C, time = 20 h). After the reaction is completed, it is dried under vacuum and ground into powder to obtain dopamine-modified sepiolite.

[0027] Preparation of modified magnesium oxide: By weight, 20 parts of magnesium oxide and 6 parts of γ-glycidoxypropyltrimethoxysilane are added to 140 parts of absolute ethanol for coupling treatment. First, stir for 4 h, then centrifuge at a speed of 8000 r / min for 6 min, and vacuum-dry the lower-layer precipitate to obtain modified magnesium oxide.

[0028] Example 1

[0029] This example provides a flame-retardant rubber waterstop for tunnels. By weight, it includes the following components: 60 parts of polyisobutene, 44 parts of modified ethylene-propylene rubber, 26 parts of carbon black, 22 parts of dopamine-modified sepiolite, 14 parts of modified magnesium oxide, 8 parts of plasticizer triphenyl phosphate, 6 parts of zinc oxide, 5 parts of stearic acid, 2.4 parts of diisopropylbenzene peroxide, and 1.6 parts of 2-mercaptobenzimidazole. The preparation method of the modified ethylene-propylene rubber includes: By weight, 40 parts of montmorillonite, 50 parts of methyltrichlorosilane, and 120 parts of absolute ethanol are mixed for stirring treatment (stirring speed = 120 rpm, temperature = 40 °C, time = 12 h), then 120 parts of tetrahydrofuran are added and dispersed evenly, and then 16 parts of 4-hydroxyphthalic anhydride and 4 parts of sodium hydride are added for anhydride reaction (reaction temperature = 30 °C, reaction time = 26 h) to obtain anhydride-modified montmorillonite; 70 parts of ethylene-propylene rubber and 12 parts of the anhydride-modified montmorillonite are subjected to mixing treatment (mixing treatment temperature = 110 °C, mixing treatment time = 12 min) to obtain modified ethylene-propylene rubber.

[0030] Example 2

[0031] This example provides a flame-retardant rubber waterstop for tunnels. By weight, it includes the following components: 56 parts of polyisobutene, 40 parts of modified ethylene-propylene rubber, 22 parts of carbon black, 18 parts of dopamine-modified sepiolite, 10 parts of modified magnesium oxide, 6 parts of plasticizer tricresyl phosphate, 4 parts of zinc oxide, 3 parts of stearic acid, 2.2 parts of diisopropylbenzene peroxide, and 1.2 parts of 2-mercaptobenzimidazole. The preparation method of the modified ethylene-propylene rubber comprises: by weight, mixing 30 parts of montmorillonite, 40 parts of methyltrichlorosilane and 100 parts of absolute ethanol for stirring treatment (stirring speed is 100 rpm, temperature is 30 °C, time is 16 h), then adding 100 parts of tetrahydrofuran to disperse evenly, and further adding 10 parts of 4-hydroxyphthalic anhydride and 2 parts of sodium hydride for anhydride reaction (reaction temperature is 26 °C, reaction time is 28 h) to obtain anhydride-modified montmorillonite; mixing 60 parts of ethylene-propylene rubber and 8 parts of the anhydride-modified montmorillonite for kneading treatment (kneading treatment temperature is 100 °C, kneading treatment time is 16 min) to obtain the modified ethylene-propylene rubber.

[0032] Example 3

[0033] This example provides a flame-retardant rubber waterstop for tunnels, by weight, comprising the following components: 58 parts of polyisobutylene, 42 parts of modified ethylene-propylene rubber, 24 parts of carbon black, 20 parts of dopamine-modified sepiolite, 12 parts of modified magnesium oxide, 7 parts of plasticizer tolyl diphenyl phosphate, 5 parts of zinc oxide, 4 parts of stearic acid, 2.3 parts of dicumyl peroxide and 1.4 parts of 2-mercaptobenzimidazole; The preparation method of the modified ethylene-propylene rubber comprises: by weight, mixing 35 parts of montmorillonite, 45 parts of methyltrichlorosilane and 110 parts of absolute ethanol for stirring treatment (stirring speed is 110 rpm, temperature is 35 °C, time is 14 h), then adding 110 parts of tetrahydrofuran to disperse evenly, and further adding 14 parts of 4-hydroxyphthalic anhydride and 3 parts of sodium hydride for anhydride reaction (reaction temperature is 28 °C, reaction time is 27 h) to obtain anhydride-modified montmorillonite; mixing 65 parts of ethylene-propylene rubber and 10 parts of the anhydride-modified montmorillonite for kneading treatment (kneading treatment temperature is 105 °C, kneading treatment time is 14 min) to obtain the modified ethylene-propylene rubber.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that commercially available ethylene-propylene rubber (grade 3092PM) is used to replace the modified ethylene-propylene rubber.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that commercially available sepiolite (CAS No. 63800-37-3) is used to replace the dopamine-modified sepiolite.

[0036] Comparative Example 3 The difference between this comparative example and Example 1 is that commercially available magnesium oxide (CAS No. 1309-48-4) is used to replace the modified magnesium oxide.

[0037] The properties of the rubber waterstops provided in the above examples and comparative examples are tested, and the test methods are as follows: (1)Tensile strength test: The test was carried out with reference to the requirements of "GB / T 18173.2-2014 Polymer waterproof materials - Part 2: Waterstops".

[0038] (2)Tear strength test: The test was carried out with reference to the requirements of "GB / T 18173.2-2014 Polymer waterproof materials - Part 2: Waterstops".

[0039] (3)Oxygen index test: The test was carried out with reference to the requirements of "GB / T 10707-2008 Determination of combustion properties of rubbers".

[0040] The above performance test data are shown in Table 1.

[0041] Table 1 Performance test results

[0042] As can be seen from the above, in the present invention, by using modified ethylene-propylene rubber, dopamine-modified sepiolite and modified magnesium oxide as the main materials, a flame-retardant rubber waterstop for tunnels (Examples 1 to 3) is prepared, and its comprehensive performance is better.

[0043] Compared with Example 1, when using commercially available ethylene-propylene rubber (grade 3092PM) to replace the modified ethylene-propylene rubber, the tensile strength decreases, the tear strength becomes smaller, and the oxygen index decreases (Comparative Example 1); compared with Example 1, when using commercially available sepiolite (CAS No. 63800-37-3) to replace the dopamine-modified sepiolite, the tensile strength decreases, the tear strength becomes smaller, and the oxygen index decreases (Comparative Example 2); compared with Example 1, when using commercially available magnesium oxide (CAS No. 1309-48-4) to replace the modified magnesium oxide, the tensile strength decreases, the tear strength becomes smaller, and the oxygen index decreases (Comparative Example 3).

[0044] In summary, in the present invention, by using modified ethylene-propylene rubber, dopamine-modified sepiolite and modified magnesium oxide as the main materials, a flame-retardant rubber waterstop for tunnels is prepared, effectively improving the tensile strength, increasing the tear strength, and obtaining good flame retardancy.

Claims

1. A flame retardant rubber water stop for tunnels, characterized in that: The invention comprises the following components in parts by weight: 56-60 parts of polyisobutylene, 40-44 parts of modified ethylene-propylene rubber, 22-26 parts of carbon black, 18-22 parts of sepiolite, 10-14 parts of magnesium oxide, 6-8 parts of plasticizer, 4-6 parts of zinc oxide, 3-5 parts of stearic acid, 2.2-2.4 parts of diisopropylbenzene peroxide and 1.2-1.6 parts of 2-mercaptobenzimidazole; The preparation method of the modified ethylene-propylene rubber comprises: mixing 30-40 parts of montmorillonite, 40-50 parts of methyltrichlorosilane and 100-120 parts of anhydrous ethanol by weight, stirring the mixture, adding 100-120 parts of tetrahydrofuran to disperse the mixture evenly, adding 10-16 parts of 4-hydroxyphthalic anhydride and 2-4 parts of sodium hydride to carry out anhydride reaction to obtain anhydride montmorillonite; and kneading 60-70 parts of ethylene-propylene rubber and 8-12 parts of the anhydride montmorillonite to obtain the modified ethylene-propylene rubber.

2. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The stirring treatment conditions include: a stirring speed of 100-120 rpm, a temperature of 30-40° C., and a time of 12-16 h.

3. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The conditions of the anhydride reaction include: a reaction temperature of 26-30° C. and a reaction time of 26-28 h.

4. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The mixing treatment conditions include: mixing treatment temperature of 100-110° C., and mixing treatment time of 12-16 min.

5. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The sepiolite is dopamine-modified sepiolite; The preparation method of dopamine-modified sepiolite comprises: dispersing 1 to 3 parts of sepiolite and 1 to 3 parts of dopamine in 400 to 500 parts of tris(hydroxymethyl)aminomethane by weight for heating reaction, vacuum drying after the reaction is completed, grinding and crushing to obtain dopamine-modified sepiolite.

6. The flame retardant rubber water stop for tunnel according to claim 5, characterized in that: The conditions of the heating reaction include: pH 8.2-8.6, temperature 70-80° C., and time 20-24 h.

7. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The magnesium oxide is modified magnesium oxide; The preparation method of the modified magnesium oxide comprises: adding 10 to 20 parts of magnesium oxide and 2 to 6 parts of γ-glycidyloxypropyltrimethoxysilane to 120 to 140 parts of anhydrous ethanol for coupling treatment to obtain the modified magnesium oxide.

8. The flame-retardant rubber waterstop for tunnel according to claim 7, characterized in that: The coupling treatment conditions include: stirring for 2 to 4 hours, then centrifuging at a speed of 7000 to 8000 r / min for 6 to 10 minutes, and vacuum drying the lower precipitate.

9. The flame-retardant rubber waterstop for tunnel according to claim 1, characterized in that: The plasticizer is selected from at least one of triphenyl phosphate, tricresyl phosphate, and toluene diphenyl phosphate.

10. A method for preparing a flame-retardant rubber waterstop for tunnels according to any one of claims 1 to 9, characterized in that: The following steps are involved: In parts by weight, 56-60 parts of polyisobutylene, 40-44 parts of modified ethylene-propylene rubber, 22-26 parts of carbon black, 18-22 parts of sepiolite, 10-14 parts of magnesium oxide, 6-8 parts of plasticizer, 4-6 parts of zinc oxide, 3-5 parts of stearic acid and 2.2-2.4 parts of diisopropylbenzene peroxide are mixed for 10-15 minutes, and then a vulcanizing agent is added and mixed for 3-5 minutes, and the mixture is allowed to stand for 12-24 hours and vulcanized to obtain a flame-retardant rubber waterstop for tunnels.

Images