Water-swellable nitrile rubber composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of rubber, in particular to a water-swellable nitrile rubber composite material as well as a preparation method and application thereof. The water-swellable nitrile rubber composite material is prepared from the following raw materials in parts by weight: 60 to 90 parts of carboxyl nitrile rubber, 10 to 40 parts of brominated butyl rubber, 40 to 60 parts of amino-terminated nitrile rubber, 40 to 60 parts of water-absorbent resin, 2 to 4 parts of stearic acid, 1 to 2 parts of microcrystalline wax, 1 to 2 parts of an anti-aging agent, 2 to 3 parts of a compatilizer, 2.4 to 3.6 parts of N, N '-dicyclohexylcarbodiimide and 10 to 30 parts of a functional aid. 6-14 parts of zinc oxide and 3-6 parts of a foaming agent; wherein the functional auxiliary agent is a compound of sodium bentonite / polyoxyethylene. The invention overcomes the problems of poorer mechanical properties, slower water absorption speed, easy dissolution of water-absorbent resin and the like of the water-swellable rubber prepared in the prior art, and also provides a simple and feasible preparation method and application of the water-swellable rubber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber, in particular to a water-swelling nitrile rubber composite material and a preparation method and application thereof. BACKGROUND

[0002] Water-swelling rubber, also known as water-absorbing rubber, is a new type of special rubber composed of a rubber matrix and a hydrophilic component. This material not only has excellent properties of rubber itself, but also has the ability to absorb water, and after absorbing water, its mass and volume can be expanded by several times. It is widely used in the fields of tunnels, subways, culverts, underwater engineering, offshore oil production, etc. due to its dual water-stopping function of elastic water-stopping and swelling water-stopping.

[0003] Rubber itself does not have the ability to absorb water. To make rubber absorb water, hydrophilic substances must be introduced into it. The method of adding hydrophilic substances mainly includes physical blending and chemical grafting modification. Physical blending refers to using physical methods to mix rubber and water-absorbing components uniformly. In this process, only physical macro-mixing occurs between the two components, and no chemical reaction occurs between the components. Physical blending is further divided into mechanical blending and emulsion blending. Mechanical blending usually refers to using mechanical mixers such as open mills and internal mixers to mix water-absorbing resins, rubber, and various components uniformly, and then preparing water-swelling rubber through vulcanization and other steps. This method has the advantages of simple preparation method and high yield, but it has the disadvantages of water-absorbing resin agglomeration, uneven dispersion of fillers, and poor mechanical properties of the prepared material. Emulsion blending refers to mixing latex and water-absorbing resins in an emulsion and then forming through a series of operations. Compared with mechanical blending, emulsion blending can control the uniformity of the finished product to a greater extent, but the cost is higher than that of mechanical blending. Chemical grafting modification refers to introducing hydrophilic groups such as hydroxyl groups, ether bonds, and carboxyl groups into the molecular chain of rubber through chemical reactions, so that rubber directly has the ability to absorb water. Rubber materials obtained by chemical grafting method have the characteristics of stable properties, but also have the disadvantages of low yield and high preparation cost. Therefore, physical blending, especially mechanical blending, has become the mainstream method for preparing water-swelling rubber.

[0004] The water absorption process of water-swelling rubber can be mainly divided into two stages. The first stage is that when water medium comes into contact with the rubber material, it gradually penetrates into the rubber interior from the surface of the rubber material and combines with the water-absorbing resin through capillary action. The second stage is that the water-absorbing resin swells under the action of water, thereby driving the rubber matrix to swell. After the rubber swells, it will produce an inward shrinkage force. When the shrinkage force and the swelling force of the water-absorbing resin balance, the water-swelling rubber reaches its maximum swelling ratio.

[0005] In the preparation of the water-swelling rubber, the rubber matrix has many choices, but in order to improve the compatibility with the water-absorbing resin and reduce the degree of mechanical strength decrease, the polar rubber is used more, such as chlorobutyl rubber, nitrile rubber, epoxy natural rubber, etc. The types of water-absorbing resin are various, such as sodium polyacrylate, polyacrylamide, modified starch water-absorbing polymer, modified cellulose water-absorbing polymer, etc.

[0006] The traditional water-swelling rubber generally has the following problems: first, the addition of water-absorbing resin in the rubber matrix, the compatibility of the two is not matched, which may cause poor mechanical properties; when the crosslinking density is large, the mechanical properties of the rubber are good, but the water-swelling expansion ratio is small, and the water-absorbing speed is slow. When the crosslinking density is small, the water-absorbing capacity is improved, but the mechanical properties are poor. The vulcanization system of the prior art is generally a sulfur vulcanization system or a peroxide vulcanization system. The characteristics of the two vulcanization systems are that the generated intermolecular crosslinking bond is a covalent bond, and the intermolecular force is large. Therefore, the resistance during the water-swelling process of the rubber is large, resulting in slow water-absorbing speed and small expansion ratio. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a water-swelling nitrile rubber composite material, which overcomes the problems of poor mechanical properties, slow water-absorbing speed and easy dissolution of water-absorbing resin of the water-swelling rubber prepared in the prior art. The present application also provides a preparation method and application thereof.

[0008] The purpose of the present application is achieved by the following technical solutions:

[0009] The water-swelling nitrile rubber composite material is made of the following raw materials by weight:

[0010] Carboxyl nitrile rubber 60-90 parts, brominated butyl rubber 10-40 parts, amino-terminated nitrile rubber 40-60 parts, water-absorbing resin 40-60 parts, stearic acid 2-4 parts, microcrystalline wax 1-2 parts, antioxidant 1-2 parts, compatibilizer 2-3 parts, N,N'-dicyclohexyl carbodiimide 2.4-3.6 parts, functional additive 10-30 parts, zinc oxide 6-14 parts, foaming agent 3-6 parts.

[0011] The functional additive is a composite of sodium bentonite / polyethylene oxide.

[0012] Preferably, the carboxyl nitrile rubber can use the following brands: Lanzhou Petrochemical XNBR3304, Zhenjiang Nandi Chemical 1072CG, Germany Lanxess NX740, etc.

[0013] Preferably, the brominated butyl rubber can be used as follows: Yanshan Petrochemical BIIR2032, BIIR2211; Germany Lanxess: BIIR2030 (Mooney viscosity 32±4, bromine content 1.8%), BIIR2222, BIIR2244; ExxonMobil: BIIR2255, BIIR2211, etc.

[0014] Preferably, the terminal amino butyl nitrile rubber refers to a liquid butyl nitrile polymer containing amino (-NH2) at the chain end, referred to as ATBN, with a number average molecular weight of 3500-4500 and an amino content of 16-19%, preferably 17%. Preferably, the brand is Hycar-ATBN (USA); Dongguan Nabaichuan Plastic Co., Ltd., terminal amino liquid butyl nitrile rubber (ATBN), number average molecular weight 3500, amino content about 17%; Jingjiang Tonggao Chemical Co., Ltd., TL55.

[0015] Preferably, the water-absorbing resin is polyacrylate with a particle size of 0.1-10 μm and a number average molecular weight of 50-500,000, preferably sodium polyacrylate, lattice momentum (Shanghai) new material technology Co., Ltd., brand: WANICE WHS 800. If the number average molecular weight is higher than 500,000, there may be dispersion problems in the rubber matrix, thereby affecting the mechanical properties of the material. If the number average molecular weight is less than 50,000, the water absorption capacity of the polyacrylate resin is limited.

[0016] Preferably, the antioxidant is antioxidant RD or antioxidant 4010NA.

[0017] Preferably, the compatibilizer is VESTENAMER 8012, Germany Evonik Industrial Group.

[0018] Preferably, the foaming agent is foaming agent H.

[0019] The rubber matrix material used in the application includes two kinds of rubber, the first is the main rubber material: carboxyl nitrile rubber, and the second is the auxiliary rubber material. The auxiliary rubber material includes brominated butyl rubber and amino-terminated nitrile rubber. The main rubber material carboxyl nitrile rubber is vulcanized by a metal oxide system to form ionic crosslinking bonds, aiming to realize that the ionic crosslinking of carboxyl nitrile rubber is partially destroyed in the process of water medium expansion, so as to realize a larger expansion ratio. The auxiliary rubber material brominated butyl rubber also uses a zinc oxide system, but it constructs stable C-C crosslinking bonds, which can ensure that the prepared rubber material has basic mechanical properties under the condition of a certain expansion ratio in the presence of water medium. The amino group in the auxiliary rubber material amino-terminated nitrile rubber interacts with the carboxyl group in the water-absorbing resin sodium polyacrylate to form a stable network, so that the water-absorbing resin sodium polyacrylate is not easy to separate from the matrix, forming a long-life and stable water-swelling rubber product. The preferred sodium bentonite / polyethylene oxide composite is used as a functional additive, which is composed of silicate and has a sub-micron layered structure, which can effectively absorb water by capillary adsorption and diffusion, and is beneficial to improve the water absorption speed of the water-swelling rubber. The foaming process is used to prepare a water-absorbing rubber composite system with high water absorption speed.

[0020] The preparation method of the water-swelling nitrile rubber composite material disclosed by the application comprises the following steps:

[0021] (1) preparing a functional additive;

[0022] A liquid phase composite modification method is used, that is, sodium bentonite (25 g) is dispersed in deionized water (300 mL), 10-30 g of polyethylene oxide with a number average molecular weight of 5000-10000 is added, and a magnetic stirrer is used for stirring until uniform; then it is frozen and dehydrated by freeze-drying to obtain a sodium bentonite / polyethylene oxide composite, that is, a functional additive.

[0023] Sodium bentonite has excellent water absorption performance, however, when sodium bentonite is applied to the rubber matrix material, there are usually problems of interface bonding and dispersion of the bentonite and the rubber matrix, that is, the addition of sodium bentonite will reduce the mechanical properties of the rubber matrix to a certain extent. The sodium bentonite / polyethylene oxide composite prepared in the application introduces polyethylene oxide molecular chains on the outer layer of sodium bentonite, which can partially solve the problems of interface bonding and dispersion of the bentonite and the rubber matrix, and the polyethylene oxide itself is soluble in water, which is helpful to increase the expansion ratio and expansion speed of the water-swelling rubber in the water medium.

[0024] (2) preparing an amino-terminated nitrile rubber and water-absorbing resin composite:

[0025] The amino-terminated butyrene rubber is mixed with the water-absorbing resin in a high-speed mixer at room temperature for 10 minutes, and N,N'-dicyclohexyl carbodiimide is added to obtain the amino-terminated butyrene rubber and water-absorbing resin composite.

[0026] The amino group at the end of the butyrene rubber can react with part of the carboxyl groups in the water-absorbing resin to form an amide bond, thereby obtaining the amino-terminated butyrene rubber and water-absorbing resin composite. On the one hand, the compatibility of the water-absorbing resin with the base rubber is improved, and on the other hand, the dispersibility of the water-absorbing resin in the base rubber is improved.

[0027] (3) The carboxyl butyrene rubber and the brominated butyl rubber are mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer, and functional additive are uniformly dispersed, and then the amino-terminated butyrene rubber and water-absorbing resin composite is added, and finally zinc oxide and foaming agent are added. After mixing is completed, the sheet is discharged, and after standing for more than 24 hours, vulcanization is performed.

[0028] The base rubber-carboxyl butyrene rubber and brominated butyl rubber are first wrapped around the roller, which can better wrap other small additives and achieve uniform dispersion of the small additives. Then the amino-terminated butyrene rubber and water-absorbing resin composite is added to make the main polymer components more uniformly dispersed. Finally, zinc oxide and foaming agent are added to prevent zinc oxide from prematurely crosslinking due to long mixing time. The foaming agent is added last to prevent it from prematurely mixing with acidic stearic acid and causing an exothermic reaction, increasing the risk of experimental safety.

[0029] In step (3), the carboxyl butyrene rubber and the brominated butyl rubber are mixed on an open mill at room temperature.

[0030] In step (3), the vulcanization temperature is 125-150°C, and the vulcanization time is 10-25 minutes.

[0031] The carboxyl butyrene rubber may undergo the following reaction during vulcanization, i.e., forming an ionic crosslinking system:

[0032]

[0033] wherein the content of x is generally 1-10%, the content of y is generally 30-70%, and the content of z is generally 20-60%.

[0034] The brominated butyl rubber may undergo the following reaction during vulcanization, i.e., forming a covalent crosslinking system:

[0035] 1) De-bromination reaction

[0036] The allyl bromide structure (—CH2—C(Br)=CH—) in the BIIR molecular chain loses hydrogen bromide (HBr) under the action of zinc oxide to form an allyl carbocation intermediate. The reaction formula is:

[0037] —CH2—C(Br)=CH— + ZnO → —CH2—C+=CH— + ZnBr2+ H2O

[0038] 2) Catalysis of zinc bromide

[0039] The generated zinc bromide (ZnBr2) acts as a Lewis acid catalyst, further promoting the dehydrobromination of BIIR to form a conjugated diene structure (—CH=CH—CH=CH—), enhancing the reactivity.

[0040] 3) Carbon-carbon bond crosslinking

[0041] Cationic polymerization of allyl carbocation with the conjugated diene structure on the adjacent molecular chain forms a stable carbon-carbon crosslinking bond (—CH2—CH=CH—CH2—). Zinc oxide maintains the reaction environment by neutralizing HBr in this process.

[0042] The water-swelling nitrile rubber composite material described in the present application can be used for waterproof plugging materials. The water-swelling nitrile rubber composite material can absorb a certain amount of water and swell in volume after contacting water, and can be used for waterproof plugging in the fields of tunnels, subways, culverts, underwater engineering, offshore oil production, etc.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] 1) The present application adopts a zinc oxide vulcanization system of carboxyl nitrile rubber and brominated butyl rubber to form different vulcanization networks of ionic crosslinking and covalent crosslinking, respectively, to construct a water-swelling rubber system.

[0045] 2) The amino group in the amino-terminated nitrile rubber interacts with the carboxyl group in the sodium polyacrylate to form a stable network, so that the water-absorbing resin sodium polyacrylate is not easy to separate from the matrix, forming a long-life and stable water-swelling rubber product.

[0046] 3) The present application selects a sodium-based bentonite / polyethylene oxide composite as a functional additive, which is composed of silicate and has a sub-micron layered structure. Sodium-based bentonite has excellent water absorption performance, however, when applied to rubber matrix materials, there are usually problems of interface bonding and dispersion between bentonite and rubber matrix, i.e. the addition of sodium-based bentonite will reduce the mechanical properties of the rubber matrix to some extent. The present application prepares a sodium-based bentonite / polyethylene oxide composite, which introduces polyethylene oxide molecular chains on the outer layer of sodium-based bentonite, which not only partially solves the problems of interface bonding and dispersion between bentonite and rubber matrix, but also polyethylene itself is soluble in water, which helps to increase the swelling ratio and swelling speed of water-swelling rubber in water medium.

[0047] The role of sodium bentonite in water-swelling rubber includes: first, sodium bentonite can reinforce the water-swelling rubber system as a reinforcing and filling aid; second, the surface of sodium bentonite contains a large number of silicon hydroxyl groups, and the surface hydrogen bond can also be used to tightly combine water molecules with hydrophilic groups to form bound water; third, the layered structure of sodium bentonite can absorb water by capillary adsorption and diffusion, which is beneficial to improve the water absorption speed of water-swelling rubber.

[0048] 4) The present application selects a foaming system, which increases the through-hole rate of the system and accelerates the water absorption speed of water-swelling rubber.

[0049] 5) The cross-linked network of the prepared expanded rubber is composed of ionic bonds and covalent bonds, which has the following advantages:

[0050] Higher mechanical properties, the tensile strength is greater than 9 MPa without adding functional additives, and the tensile strength of the rubber material is more than 14 MPa after being reinforced by functional additives. When the expansion ratio is 4 times, the tensile strength is still more than 6 MPa; faster water absorption speed and larger expansion ratio, which can expand to more than 4 times of itself in pure water within 6 hours. DETAILED DESCRIPTION

[0051] In order to enable the personnel in the technical field to better understand the technical solutions in the present application, the technical solutions of the present application will be clearly and completely described below in combination with the embodiments of the present application.

[0052] The compatibilizer used in the embodiment is VESTENAMER 8012, Germany Wanheng Industrial Group

[0053] Example 1

[0054] The water-swelling nitrile rubber composite material is made of the following raw materials by weight:

[0055] Carboxyl nitrile rubber (Zhenjiang Nandi Chemical 1072CG) 60 parts, brominated butyl rubber [Germany Lanxess BIIR2244)] 40 parts, amino-terminated nitrile rubber [Hycar-ATBN (USA)] 40 parts, sodium polyacrylate [Lattice Momentum (Shanghai) New Material Technology Co., Ltd., brand: WANICE WHS 800] 40 parts, stearic acid 2 parts, microcrystalline wax 1 part, antioxidant RD 1 part, compatibilizer 2 parts, N,N'-dicyclohexyl carbodiimide 2.4 parts, sodium bentonite / polyethylene oxide composite 15 parts, zinc oxide 6 parts, foaming agent H 3 parts.

[0056] The preparation method comprises the following specific steps:

[0057] (1) Preparation of sodium bentonite / polyethylene oxide composite;

[0058] Liquid phase composite modification method was adopted, i.e. sodium bentonite (7.5g) was dispersed in deionized water (300mL), polyethylene oxide (number average molecular weight 5000-10000) 7.5g was added, and magnetic stirrer was used for stirring; then it was frozen and dehydrated by freeze drying; sodium bentonite / polyethylene oxide composite, i.e. functional additive, was obtained.

[0059] (2) Preparation of amino-terminated butyl nitrile rubber and water-absorbing resin composite:

[0060] Amino-terminated butyl nitrile rubber and water-absorbing resin were mixed in an intermeshing machine at room temperature for 10 min, and N,N'-dicyclohexyl carbodiimide was added to obtain amino-terminated butyl nitrile rubber and water-absorbing resin composite;

[0061] (3) Carboxyl butyl nitrile rubber and brominated butyl rubber were mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer and functional additive were added and dispersed uniformly, then amino-terminated butyl nitrile rubber and water-absorbing resin composite was added, and finally zinc oxide and blowing agent were added, and after mixing, the mixture was sheeted, and after standing for 24 h, vulcanization was carried out, with vulcanization temperature being 140℃ and vulcanization time being 15 min.

[0062] The test data of the water-swelling butyl nitrile rubber composite prepared in Example 1 are shown in Table 1.

[0063] The test method used is as follows:

[0064] Tensile strength was tested according to standard ASTM D412, with sample size being 50×6.25×3.2mm and test speed being 500mm / min.

[0065] Elongation at break was tested according to standard ASTM D412, with sample size being 50×6.25×3.2mm and test speed being 500mm / min.

[0066] Stress at a given elongation was tested according to standard ASTM D412, with sample size being 50×6.25×3.2mm and test speed being 500mm / min.

[0067] Swelling ratio was tested according to national standard GB / T 18173.3-2014 "High Polymer Waterproof Materials Part 3: Water-Swelling Rubber".

[0068] Size requirement: length and width were each (20.0±0.2)mm, and thickness was (2.0±0.2)mm, with 3 samples in each group.

[0069] The test method used was weighing method:

[0070] 1) Initial mass measurement: The mass of the sample in air (m 1 ) and in distilled water (m 2 ) was measured using a balance with an accuracy of 0.001 g.

[0071] 2) Immersion treatment: The sample was completely immersed in 300 mL of distilled water at (23±5) °C for a period of time, avoiding overlapping.

[0072] 3) Post-immersion measurement: The sample was removed, surface moisture was absorbed, and the mass in air (m 3 ) and in water (m 4 ) was measured.

[0073] Calculation formula:

[0074]

[0075] The arithmetic mean of 3 samples was taken.

[0076] Table 1 Test data of water-swelling nitrile rubber composite prepared in Example 1

[0077]

[0078] Example 2

[0079] The water-swelling nitrile rubber composite was prepared from the following raw materials by weight:

[0080] Carboxyl nitrile rubber (Zhenjiang Nandi Chemical 1072CG) 90 parts, brominated butyl rubber [Germany Lanxess BIIR2244)] 10 parts, amino-terminated nitrile rubber [Hycar-ATBN (USA)] 60 parts, sodium polyacrylate [Lattice Momentum (Shanghai) New Material Technology Co., Ltd., brand: WANICE WHS 800] 60 parts, stearic acid 4 parts, microcrystalline wax 2 parts, antioxidant RD 2 parts, compatibilizer 3 parts, N,N'-dicyclohexyl carbodiimide 3.6 parts, sodium-based bentonite / polyethylene oxide composite 30 parts, zinc oxide 14 parts, foaming agent H 6 parts.

[0081] The preparation method, the specific steps are as follows:

[0082] (1) Preparation of sodium-based bentonite / polyethylene oxide composite;

[0083] The liquid phase composite modification method was adopted, i.e. sodium-based bentonite (15 g) was dispersed in deionized water (300 mL), polyethylene oxide (number average molecular weight 5000-10000) 15 g was added, and magnetic stirrer was used for stirring until uniform; then it was frozen and dehydrated by freeze-drying; sodium-based bentonite / polyethylene oxide composite, i.e. functional additive, was obtained.

[0084] (2) Preparation of the amino-terminated butyrene rubber and water-absorbing resin composite:

[0085] The amino-terminated butyrene rubber and water-absorbing resin were mixed in an intermeshing machine at room temperature for 10 min, and N,N'-dicyclohexyl carbodiimide was added to obtain the amino-terminated butyrene rubber and water-absorbing resin composite;

[0086] (3) The carboxyl butyrene rubber and brominated butyl rubber were mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer, and functional additive were uniformly dispersed, and then the amino-terminated butyrene rubber and water-absorbing resin composite was added, and finally zinc oxide and foaming agent were added. After mixing was completed, the sheet was discharged, and after standing for 24 h, vulcanization was performed at a vulcanization temperature of 125°C and a vulcanization time of 25 min.

[0087] The test data of the water-swelling butyrene rubber composite prepared in Example 2 are shown in Table 2.

[0088] Table 2 Test data of the water-swelling butyrene rubber composite prepared in Example 2

[0089]

[0090] The expansion speed of the formula in Example 2 is very fast, and the expansion ratio reaches 780% at 8 h.

[0091] The reason is: first, a large amount of water-absorbing resin is added, i.e. 60 parts of sodium polyacrylate are added; second, a large amount of functional additive is added, i.e. 30 parts of sodium bentonite / polyethylene oxide composite are added.

[0092] Example 3

[0093] The water-swelling butyrene rubber composite is made of the following raw materials in parts by weight:

[0094] Carboxyl butyrene rubber (Zhenjiang Nandi Chemical 1072CG) 90 parts, brominated butyl rubber [Germany Lanxess BIIR2244)] 10 parts, amino-terminated butyrene rubber [Hycar-ATBN (USA)] 50 parts, sodium polyacrylate [Lattice Momentum (Shanghai) New Material Technology Co., Ltd., brand: WANICE WHS 800] 50 parts, stearic acid 2 parts, microcrystalline wax 1.5 parts, antioxidant 4010NA 1.5 parts, compatibilizer 2 parts, N,N'-dicyclohexyl carbodiimide 3 parts, sodium bentonite / polyethylene oxide composite 15 parts, zinc oxide 9 parts, and foaming agent H 3 parts.

[0095] The preparation method comprises the following specific steps:

[0096] (1) Preparation of the sodium bentonite / polyethylene oxide composite;

[0097] The liquid phase composite modification method is adopted, i.e. sodium bentonite (7.5 g) is dispersed in deionized water (300 mL), polyethylene oxide (number average molecular weight 5000-10000) 7.5 g is added, and a magnetic stirrer is used for stirring until uniform; then it is frozen, and dehydrated by freeze-drying; and a sodium bentonite / polyethylene oxide composite, i.e. a functional additive, is obtained.

[0098] (2) Preparation of the amino-terminated butyl nitrile rubber and water-absorbing resin composite:

[0099] The amino-terminated butyl nitrile rubber and water-absorbing resin are mixed in an intermeshing machine at room temperature for 10 min, and N,N'-dicyclohexyl carbodiimide is added to obtain the amino-terminated butyl nitrile rubber and water-absorbing resin composite;

[0100] (3) The carboxyl-terminated butyl nitrile rubber and brominated butyl rubber are mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer and functional additive are added and dispersed uniformly, then the amino-terminated butyl nitrile rubber and water-absorbing resin composite is added, and finally zinc oxide and blowing agent are added, and after mixing, the mixture is discharged, and after standing for 24 h, vulcanization is carried out, with a vulcanization temperature of 150°C and a vulcanization time of 10 min.

[0101] The test data of the water-swelling butyl nitrile rubber composite prepared in Example 3 are shown in Table 3.

[0102] Table 3 Test data of the water-swelling butyl nitrile rubber composite prepared in Example 3

[0103]

[0104] Example 4

[0105] The water-swelling butyl nitrile rubber composite is prepared from the following raw materials in parts by weight:

[0106] Carboxyl-terminated butyl nitrile rubber (Tianjin Nandihua Chemical 1072CG) 70 parts, brominated butyl rubber [Lanxess BIIR2244, Germany] 30 parts, amino-terminated butyl nitrile rubber [Hycar-ATBN, USA] 50 parts, sodium polyacrylate [WANICE WHS 800, Shanghai Lattice Momentum New Material Technology Co., Ltd.] 50 parts, stearic acid 3 parts, microcrystalline wax 1.5 parts, antioxidant RD 1.5 parts, compatibilizer 2.5 parts, N,N'-dicyclohexyl carbodiimide 3 parts, sodium bentonite / polyethylene oxide composite 20 parts, zinc oxide 9 parts, and blowing agent H 4 parts.

[0107] The preparation method comprises the following specific steps:

[0108] (1) Preparation of the sodium bentonite / polyethylene oxide composite:

[0109] The liquid phase composite modification method is used, i.e. sodium bentonite (10 g) is dispersed in deionized water (300 mL), polyethylene oxide (number average molecular weight 5000-10000) 10 g is added, and a magnetic stirrer is used for stirring until uniform; then it is frozen and dehydrated by freeze drying; and a sodium bentonite / polyethylene oxide composite, i.e. a functional additive, is obtained.

[0110] (2) Preparation of an amino-terminated butyl nitrile rubber and water-absorbing resin composite:

[0111] The amino-terminated butyl nitrile rubber and water-absorbing resin are mixed in an intermeshing machine at room temperature for 10 min, and N,N'-dicyclohexyl carbodiimide is added to obtain an amino-terminated butyl nitrile rubber and water-absorbing resin composite;

[0112] (3) The carboxyl-terminated butyl nitrile rubber and brominated butyl rubber are mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer and functional additive are added and dispersed uniformly, then the amino-terminated butyl nitrile rubber and water-absorbing resin composite is added, and finally zinc oxide and blowing agent are added, and after mixing is completed, the mixture is discharged, and after standing for 24 h, vulcanization is carried out, with a vulcanization temperature of 130°C and a vulcanization time of 20 min.

[0113] The test data of the water-swelling butyl nitrile rubber composite prepared in Example 4 are shown in Table 4.

[0114] Table 4 Test data of the water-swelling butyl nitrile rubber composite prepared in Example 4

[0115]

[0116]

[0117] Comparative Example 1

[0118] The water-swelling butyl nitrile rubber composite is prepared from the following raw materials in parts by weight:

[0119] Carboxyl-terminated butyl nitrile rubber (Tianjin Nan Di Chemical 1072CG) 70 parts, brominated butyl rubber [Lanxess BIIR2244, Germany] 30 parts, amino-terminated butyl nitrile rubber [Hycar-ATBN, USA] 50 parts, sodium polyacrylate [WANICE WHS 800, Shanghai Lattice Momentum New Material Technology Co., Ltd.] 50 parts, stearic acid 3 parts, microcrystalline wax 1.5 parts, antioxidant RD 1.5 parts, compatibilizer 2.5 parts, N,N'-dicyclohexyl carbodiimide 3 parts, sodium bentonite 20 parts, zinc oxide 9 parts, and blowing agent H 4 parts.

[0120] The preparation method comprises the following specific steps:

[0121] (1) Preparation of amino-terminated nitrile rubber and water-absorbing resin composite:

[0122] The amino-terminated nitrile rubber and the water-absorbing resin were mixed in a meshing machine at room temperature for 10 minutes, and N,N'-dicyclohexylcarbodiimide was added to obtain a composite of the amino-terminated nitrile rubber and the water-absorbing resin;

[0123] (2) Carboxyl nitrile rubber and brominated butyl rubber are mixed on an open mill, stearic acid, microcrystalline wax, antioxidant, compatibilizer, and functional additives are added and dispersed evenly, and then the amino-terminated nitrile rubber and water-absorbing resin complex are added, and finally zinc oxide and foaming agent are added. After mixing, the sheet is removed and left to stand for 24 hours before vulcanization. The vulcanization temperature is 130°C and the vulcanization time is 20 minutes.

[0124] The test data of the water-swellable nitrile rubber composite material prepared in Comparative Example 1 are shown in Table 5.

[0125] Table 5 Test data of water-swellable nitrile rubber composite material prepared in Comparative Example 1

[0126]

[0127]

[0128] Comparing Example 4 with Comparative Example 1, it was found that when sodium bentonite alone was used as the functional additive, the tensile strength of the water-swellable rubber material decreased by approximately 2 MPa, and the mechanical properties decreased accordingly, compared to when the sodium bentonite / polyethylene oxide complex was added. This result suggests that the sodium bentonite / polyethylene oxide complex may improve the compatibility of the base rubber with the sodium bentonite, and that the polyethylene oxide also increases the water-swelling properties of the rubber composite system. Therefore, in terms of performance, the sodium bentonite / polyethylene oxide complex in the water-swellable rubber formulation can not only improve the mechanical properties of the rubber to a certain extent, but also increase the water-swelling rate of the water-swellable nitrile rubber composite system to a certain extent.

[0129] Comparative Example 2

[0130] The water-swellable rubber composite material is made from the following raw materials in parts by weight:

[0131] Natural rubber (Vietnam Heng Viscose SVRCV60): 100 parts;

[0132] Sodium polyacrylate [Lattice Momentum (Shanghai) New Material Technology Co., Ltd., brand: WANICE WHS 800]: 50 parts;

[0133] Maleic anhydride grafted elastomer (maleic anhydride grafted ethylene propylene rubber, Dongguan Shengli New Materials Co., Ltd., brand: XH2160X8WAIW): 5 parts;

[0134] Zinc oxide: 5 parts;

[0135] Sulfur: 2 parts;

[0136] Carbon black: 30 parts.

[0137] The preparation method is as follows:

[0138] The natural rubber is mixed on a mixer, maleic anhydride grafted elastomer, modified superabsorbent resin and carbon black are added, and finally sulfur and zinc oxide are added, and the mixing is completed, and then the rubber is discharged and stored for more than 24 hours before vulcanization, the vulcanization temperature is 150 DEG C, and the vulcanization time is 20 minutes.

[0139] The test data of the water-swelling rubber composite material prepared in Comparative Example 2 are shown in Table 6.

[0140] Table 6 Test data of water-swelling rubber composite material prepared in Comparative Example 2

[0141]

[0142] By comparing the data of Comparative Example 2 and the examples, it can be seen that the water-swelling nitrile rubber composite material prepared by using the formula and preparation method of the application has the following advantages: first, high mechanical properties; second, fast water absorption speed; and third, greater water absorption.

Claims

1. A water-swellable nitrile rubber composite, characterized by: It is made from the following raw materials by weight parts: Carboxyl nitrile rubber 60-90 parts, brominated butyl rubber 10-40 parts, amino-terminated nitrile rubber 40-60 parts, water-absorbing resin 40-60 parts, stearic acid 2-4 parts, microcrystalline wax 1-2 parts, antioxidant 1-2 parts, compatibilizer 2-3 parts, N,N'-dicyclohexyl carbodiimide 2.4-3.6 parts, functional additive 10-30 parts, zinc oxide 6-14 parts, foaming agent 3-6 parts; The functional additive is a composite of sodium bentonite / polyethylene oxide.

2. The water-swellable nitrile rubber composite of claim 1, wherein: The number average molecular weight of the amino-terminated nitrile rubber is 3500-4500, and the amino content is 16-19%.

3. The water-swellable nitrile rubber composite of claim 1, wherein: The water-absorbing resin is polyacrylate with a particle size of 0.1-10 μm and a number average molecular weight of 50-500 thousand.

4. The water-swellable nitrile rubber composite of claim 1, wherein: The antioxidant is antioxidant RD or antioxidant 4010NA.

5. The water-swellable nitrile rubber composite of claim 1, wherein: The compatibilizer is VESTENAMER 8012.

6. The water-swellable nitrile rubber composite of claim 1, wherein: The foaming agent is foaming agent H.

7. A process for the production of a water-swellable nitrile rubber composite according to any one of claims 1 to 6, characterized in that: The following steps are included: (1) Preparation of functional additive; The liquid phase composite modification method is adopted, i.e. sodium bentonite is dispersed in deionized water, and polyethylene oxide with a number average molecular weight of 5000-10000 is added thereto, and then stirred uniformly by a magnetic stirrer; and then it is frozen and dehydrated by freeze-drying to obtain the composite of sodium bentonite / polyethylene oxide, i.e. the functional additive; (2) Preparation of amino-terminated nitrile rubber / water-absorbing resin composite: The amino-terminated nitrile rubber and the water-absorbing resin are mixed in a high-speed mixer at room temperature, and N,N'-dicyclohexyl carbodiimide is added to obtain the amino-terminated nitrile rubber / water-absorbing resin composite; (3) Carboxyl nitrile rubber and brominated butyl rubber are mixed on an open mill, and stearic acid, microcrystalline wax, antioxidant, compatibilizer, functional additive are dispersed uniformly, then the amino-terminated nitrile rubber / water-absorbing resin composite is added, and finally zinc oxide and foaming agent are added, and after mixing, the sheet is cut, and after standing for more than 24 h, vulcanization is carried out.

8. The method of claim 7, wherein the water-swelling nitrile rubber composite is prepared by the steps of: (1) mixing the nitrile rubber, the water-soluble polymer, and the water to form a mixture; (2) extruding the mixture to form a sheet; and (3) drying the sheet. In step (3), carboxyl nitrile rubber and brominated butyl rubber are mixed on an open mill at room temperature.

9. The method for preparing the water-swellable nitrile rubber composite material according to claim 7, wherein: In step (3), the vulcanization temperature is 125-150℃, and the vulcanization time is 10-25 min.

10. Use of a water-swellable nitrile rubber composite according to any one of claims 1-6, characterized in that: It is used for waterproof plugging material.

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