CN102875700B - Method for modifying rubber base of water swelling nitrile rubber - Google Patents

Abstract

The invention relates to a rubber-based modification method for water-absorbing swellable nitrile rubber, which includes the following steps: after completely dissolving 3 g of nitrile rubber with 30 mL of solvent, place it in an ice water bath, and slowly add 0.5 to 2.5 mL of nitrile rubber in sequence. Stir the strong alkaline solution and 2 to 10 g of hydrogen peroxide solution in an ice bath for 1 to 2.5 hours, then raise the temperature to 20 to 50°C and react at a constant temperature for 16 to 36 hours. After the reaction is completed, use an inorganic acidic solution to adjust the reaction product to pH 5 to 6 , then wash it with distilled water several times, place it in a vacuum drying oven and dry it at 30~40°C to obtain modified hydrophilic nitrile rubber. The invention has the following beneficial effects: the water-absorbing swellable nitrile rubber prepared by this method does not need to add a compatibilizer, and only needs to utilize the hydrophilicity of the modified hydrophilic nitrile rubber to achieve uniform blending with the water-absorbing components. The purpose is to save costs, the preparation method is simple, and the equipment requirements are low.

Description

A kind of rubber-based modification method of water-absorbing swellable nitrile rubber

technical field

The invention relates to a rubber-based modification method for water-absorbing swellable nitrile rubber, which belongs to the field of sealing materials.

technical background

Water-swelling Rubber (WSR for short) is a new type of functional polymer material made by introducing hydrophilic groups or water-absorbing components into the rubber matrix. Since its appearance in the late 1970s and early 1980s, water-swellable rubber has attracted people's attention because of its unique dual water-stop function of elastic sealing and water-swelling water-stop. It can be widely used in the waterproofing of building deformation joints, construction joints, underwater instruments and military weapons, as well as the joint waterproofing and sealing of metal, concrete, ceramics, plastics, steel and other pipes and box culverts. Compared with traditional pressure sealing materials, water-absorbing swellable rubber not only has the sealing effect of conventional water-stop materials, but also can play the role of water-stopping. Water-absorbing swellable rubber can realize its sealing and waterproof function with a slight pressure Eliminate the damage caused by compressive stress, and it is convenient for construction, saves materials and reduces project cost. WSR is an alternative waterproof sealing material, therefore, it has a good application prospect and a huge market.

The most commonly used method in industry is to use the physical blending method to prepare water-swelling rubber (that is, the hydrophilic component is blended with the rubber matrix), wherein the distribution and particle size of the hydrophilic component have a significant impact on the water-swellable rubber prepared by the physical blending method. The water absorption and mechanical properties of water-swellable rubber have a great influence. For the hydrophilic component, the larger the particle size and the higher the content of the component, the worse the compatibility in the rubber during blending, so that the mechanical properties of the prepared water-swellable rubber are also worse. If the particle size of the hydrophilic component is smaller and the nanoscale dispersion can be achieved in the rubber, the mechanical properties and water absorption properties of the hydrophilic component to the water-swellable rubber will be smaller. However, if the hydrophilic component wants to achieve nanoscale dispersion, its particle size must be nanoscale. For the hydrophilic component, the smaller the particle size, the larger the specific surface area and the higher the surface energy. Agglomeration is easy to occur, which leads to poor compatibility when blended with rubber, so that the hydrophilic components cannot be uniformly dispersed in the rubber matrix, resulting in a significant decline in water absorption and mechanical properties of WSR.

Contents of the invention

The technical problem to be solved by the present invention is to provide a rubber matrix modification method for water-absorbing swellable nitrile rubber for the above-mentioned prior art, and the rubber matrix obtained by it can be better mixed with water-absorbing components, thereby solving the problem of water-absorbing The problem of poor compatibility of expanded nitrile rubber.

The technical route adopted by the present invention to solve the above-mentioned technical problems is: a rubber-based modification method of water-absorbing swellable nitrile rubber, comprising the following steps: after 3g of nitrile rubber is completely dissolved with 30mL solvent, it is placed in an ice-water bath , slowly add 0.5~2.5mL of strong alkaline solution and 2~10g of hydrogen peroxide solution in turn, stir in ice bath for 1~2.5h, then raise the temperature to 20~50℃, and react at constant temperature for 16~36h. After the reaction, use inorganic The acidic solution adjusts the reaction product to pH 5~6, and then washes it several times with distilled water, and puts it in a vacuum drying oven to dry at 30~40°C to obtain a modified hydrophilic nitrile rubber.

According to the above scheme, the described nitrile rubber is nitrile rubber with a nitrile content of 30% to 45%, in molar percentage.

According to the above scheme, the solvent is tetrahydrofuran, acetone, xylene, toluene or chlorobenzene.

According to the above scheme, the strong alkaline solution is NaOH or KOH aqueous solution with a concentration of 4-6 mol/L.

According to the above scheme, the concentration of the hydrogen peroxide solution is 30wt%.

According to the above scheme, the inorganic acidic solution is dilute hydrochloric acid aqueous solution.

In the nitrile rubber of the present invention, under the environment of strong alkali hydrogen peroxide, the nitrile group is partially hydrolyzed into an amide group first, and then under ^OH- , the amide group continues to be hydrolyzed into a carboxyl group, thereby enhancing the hydrophilicity of the nitrile rubber and obtaining a modified Hydrophilic rubber.

The obtained modified hydrophilic nitrile rubber of the present invention can be used for preparing water-absorbing swellable nitrile rubber, and it can adopt following technical scheme: a kind of preparation method of water-absorbing swellable nitrile-butadiene rubber, its steps are as follows:

1) The parts by weight of each raw material are: 100 parts of modified hydrophilic nitrile rubber, 1.5 parts of activator A, 5 parts of activator B, 1 part of anti-aging agent, 20 parts of carbon black, and 2 parts of vulcanization accelerator A Parts, 2 parts of vulcanization accelerator B, 0.5~2.5 parts of vulcanizing agent, 40~80 parts of water-absorbing resin, 4-12 parts of water-absorbing auxiliary agent, 10-50 parts of white carbon black, select modified hydrophilic nitrile rubber, active agent A, active agent B, anti-aging agent, carbon black, vulcanization accelerator A, vulcanization accelerator B, vulcanization agent, water-absorbing resin, water-absorbing aid and white carbon black, spare;

2) After masticating the modified hydrophilic nitrile rubber on the open mill for 1 min, add activator A, activator B, vulcanizing agent, anti-aging agent, and water-absorbing additive in sequence, and roll the mixture at a roll distance of 2mm. After kneading evenly for 3 minutes, add water-absorbing resin and knead evenly, then add carbon black and white carbon black, and knead for 10 minutes at a roll distance of 3mm. Finally, add vulcanization accelerator A and vulcanization accelerator B to the water-absorbing swelling rubber matrix Mix evenly, under the roller distance is 0.4mm, make a triangular bag 6 times, thin pass, the next sheet, leave standstill for 4 hours, obtain the well-mixed unvulcanized water-swellable nitrile rubber for subsequent use;

3) Put the kneaded unvulcanized water-absorbing swellable nitrile rubber obtained in step 2) into a tableting mold, and vulcanize it on a flat vulcanizer at 160°C for 25 minutes, the vulcanization pressure is 10Mpa, open the mold, and take out the vulcanization Good water-swellable nitrile rubber, let it stand for 24 hours, and cut the sample.

According to the above scheme, the active agent A is stearic acid, and the active agent B is ZnO.

According to the above scheme, the anti-aging agent is anti-aging agent D, anti-aging agent FD or anti-aging agent DNP.

According to the above scheme, the carbon black is natural gas channel black.

According to the above scheme, the vulcanization accelerator A is accelerator DM or accelerator M.

According to the foregoing scheme, described vulcanization accelerator B is accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide).

According to the above scheme, the vulcanizing agent is sulfur (sublimed sulfur).

According to the above scheme, the water-absorbing resin is sodium polyacrylate or lithium polyacrylate.

According to the above scheme, the water absorption aid is PEG-6000 or PEG-8000.

According to the above scheme, the white carbon black is fumed white carbon black.

The modified hydrophilic nitrile rubber of the present invention's gained prepares the action principle of water-absorbing swellable nitrile rubber material as follows:

                                                 

Water-absorbing swellable rubber is mainly prepared by physical and mechanical blending of rubber and water-absorbing resin. Because rubber has low polarity and poor hydrophilicity, water-absorbing resin has good hydrophilicity and strong polarity, resulting in compatibility between the two. Poor sex. In the present invention, the nitrile group of the nitrile rubber is partially hydrolyzed into an amide group or a carboxyl group, so that the hydrophilicity of the nitrile rubber is enhanced, so that it can be better blended with the water-absorbing component, and then the poor compatibility of the water-absorbing swelling rubber is improved. The problem.

The present invention has following advantage and beneficial effect:

The method of the modified hydrophilic nitrile rubber prepared by the present invention is to utilize part of the nitrile groups on the nitrile rubber to be hydrolyzed into amide groups or carboxyl groups, so that its hydrophilicity is enhanced, and then the modified hydrophilic nitrile rubber is used to prepare water-absorbing swelling rubber. Compared with the water-absorbent swellable nitrile rubber prepared by the traditional method, the water-absorbent swellable nitrile rubber prepared by this method does not need to add a compatibilizer, and only needs to use the hydrophilicity of the modified hydrophilic nitrile rubber to achieve its compatibility with water absorption. The purpose of uniform blending of components, thereby saving costs, simple preparation method, low equipment requirements, can be widely used in tunnels, culverts, swimming pools, basements, underwater projects, underground oil production, water supply facilities and civil construction.

Description of drawings

Fig. 1 is the infrared spectrum of nitrile rubber in the embodiment of the present invention 1;

Fig. 2 is the infrared spectrum of the modified hydrophilic nitrile rubber in Example 1 of the present invention.

Detailed ways

For a better understanding of the present invention, the following examples are further descriptions of the present invention, but the content of the present invention is not limited to the following examples.

Example 1

The preparation of modified hydrophilic nitrile rubber, its preparation steps are as follows:

After all dissolving 3g of nitrile rubber with 30% molar percentage of nitrile group with 30mL of tetrahydrofuran, it was placed in an ice-water bath, and slowly added successively 1.0mL of 4mol/L NaOH aqueous solution and 8g of 30wt% hydrogen peroxide solution to stir on ice After bath reaction for 1 hour, the temperature was raised to 40°C, and the constant temperature reaction was carried out for 28 hours. After the reaction, the reaction product was adjusted to weak acidity (pH 5~6) with dilute hydrochloric acid aqueous solution, and then washed several times with a large amount of distilled water, and placed in a vacuum Dry in a drying oven at 40°C to obtain a modified hydrophilic nitrile rubber.

The infrared spectrum of the nitrile rubber in Fig. 1 corresponds to the characteristic absorption of the acrylonitrile chain segment is 2240cm ^-1 (the stretching vibration of the nitrile group) and 1440cm ^-1 (the bending vibration of CH ₂ ), and the absorption corresponding to the butadiene is also 968cm ^-1 is the bending vibration peak of anti-1,4-polybutadiene γ(=CH), 2847cm ^-1 and 2920cm ^-1 are the symmetric stretching vibration of ν _s (CH ₂ ) and the non-symmetrical vibration of ν _as (CH ₂ ), respectively Symmetrical vibration, 1350 is the in-plane bending vibration of δ _s (CH ₃ ). Compared with the modified hydrophilic nitrile rubber in Figure 1 and Figure 2, the characteristic peaks of the nitrile group in Figure 2 are obviously weakened, and there are newly added 1260 cm ^-1 (stretch vibration of CO), 1640 cm ^-1 (stretch vibration of C=O Stretching vibration) and 3419cm ^-1 (stretching vibration of OH), so the new vibration peak shows that a small amount of -COOH is generated. Utilizing the principle of hydrolyzing the nitrile group of the nitrile rubber, the partial hydrolysis of the nitrile group makes the hydrophilicity of the nitrile rubber stronger, and then provides the feasibility for preparing the water-absorbing swellable nitrile rubber with good compatibility.

Example 2

After the toluene of 30mL of the toluene of 35% nitrile group content molar percentage of 3g is dissolved completely, it is placed in the ice-water bath, the NaOH aqueous solution of the 5mol/L of 2.0mL and 6g 30wt% hydrogen peroxide aqueous solution are stirred successively and ice-cold After bath reaction for 1.5h, the temperature was raised to 50°C, and the reaction was carried out at constant temperature for 24h. After the reaction, the reaction product was adjusted to weak acidity (pH5~6) with dilute aqueous hydrochloric acid solution, then, washed several times with a large amount of distilled water, and dried in a vacuum oven at 30°C to obtain modified hydrophilic nitrile rubber.

Example 3

After the nitrile rubber of 40% nitrile group content molar percentage of 3g is dissolved completely with the acetone of 30mL, it is placed in the ice-water bath, the KOH aqueous solution of the 6mol/L of 2.5mL and the 4g 30wt% hydrogen peroxide aqueous solution are stirred successively and stirred on ice After 2 hours of reaction in the bath, the temperature was raised to 30°C, and the reaction was carried out at a constant temperature for 32 hours. After the reaction, the reaction product was adjusted to weak acidity (pH5~6) with dilute hydrochloric acid aqueous solution, then, washed several times with a large amount of distilled water, and dried in a vacuum oven at 40°C to obtain modified hydrophilic nitrile rubber.

Application Examples 1~5

Utilize modified hydrophilic nitrile rubber to prepare the specific application of water-absorbing swellable nitrile rubber, and its steps are as follows:

1) After 100 parts of the modified hydrophilic nitrile rubber obtained in Example 1 were masticated on the open mill for 1 min, 1.5 parts of stearic acid, 5 parts of ZnO, 0.5 parts of sublimed sulfur, 1 part of anti-aging agent D, 8 parts of PEG-6000, knead evenly at a roller distance of 2mm (about 3min), then add 40~80 parts of water-absorbing resin sodium polyacrylate and knead evenly, then add reinforcing 20 parts of carbon black and 20 parts of white carbon black as fillers were kneaded for 10 minutes at a roll distance of 3 mm. Finally, 2 parts of vulcanization accelerator M and 2 parts of vulcanization accelerator CZ were added to the water-swellable rubber matrix and mixed. The kneading is uniform, under the roller distance is 0.4mm, the triangular bag is made 6 times, the thin pass, the next sheet, and stand for 4 hours to obtain the unvulcanized water-absorbing nitrile rubber that has been kneaded for subsequent use;

2) Put the kneaded unvulcanized water-absorbing swellable nitrile rubber in a tableting mold, vulcanize it on a flat vulcanizer at 160°C for 25 minutes (pressure is 10Mpa), open the mold, and take out the vulcanized water-absorbing swellable nitrile Rubber, let stand for 24 hours, and cut the sample.

Note: The weight water absorption rate and weight loss rate of water-swellable nitrile rubber are calculated as follows:

Cut the water-absorbing swellable nitrile rubber prepared by modified hydrophilic nitrile rubber into a sample of a certain weight, and immerse it in tap water or other salt water with different concentrations, take it out and weigh it at a certain temperature at regular intervals, and weigh it every When weighing for the first time, use filter paper to quickly absorb the water on the surface of the sample until the water absorption reaches saturation, and then dry it at 50°C to constant weight. Wherein the weight water absorption rate and weight loss rate of water-absorbing swellable nitrile rubber are calculated according to the following formula:

            吸水膨胀丁腈橡胶的硫化试样的硬度根据标准GB/T531测试，拉伸强度和扯断伸长率根据标准GB/T528测试。

The hardness of the vulcanized sample of water-swellable nitrile rubber is tested according to standard GB/T531, and the tensile strength and elongation at break are tested according to standard GB/T528.

The formulation and test results are shown in Table 1,

Table 1

 

Application Examples 6~10

1) After 100 parts of the modified hydrophilic nitrile rubber obtained in Example 2 were masticated on the open mill for 1 min, 1.5 parts of stearic acid, 5 parts of ZnO, 0.5 parts of sublimed sulfur, 1 part of anti-aging agent FD, 4~12 parts of PEG-8000, knead evenly at a roll distance of 2 mm (about 3 minutes), then add 60 parts of water-absorbing resin sodium polyacrylate and knead evenly, then add reinforcement 20 parts of carbon black and 20 parts of white carbon black as fillers were milled for 10 minutes at a roll distance of 3 mm. Finally, 2 parts of vulcanization accelerator DM and 2 parts of vulcanization accelerator CZ were added to the rubber matrix and mixed evenly , under the roller distance is 0.4mm, make a triangular bag 6 times, thin pass, the next sheet, leave standstill for 4 hours, to obtain the unvulcanized water-absorbing nitrile rubber that has been mixed for subsequent use;

2) Put the kneaded unvulcanized water-absorbing swellable nitrile rubber in a tableting mold, vulcanize it on a flat vulcanizer at 160°C for 25 minutes (pressure is 10Mpa), open the mold, and take out the vulcanized water-absorbing swellable nitrile Rubber, let stand for 24 hours, and cut the sample. The performance test method of the vulcanized sample is the same as that of the application examples 1-5.

Formulation and test result are shown in Table 2,

 

Application Examples 11~15

1) After putting 100 parts of the modified hydrophilic nitrile rubber obtained in Example 3 on the open mill for 1 min, add 1.5 parts of stearic acid, 5 parts of ZnO, 0.5 parts of sublimed sulfur, 1 part of anti-aging agent DNP, 8 parts of PEG-6000, knead evenly at a roll distance of 2 mm (about 3 minutes), then add 60 parts of water-absorbing resin lithium polyacrylate and knead evenly, then add reinforcing filler 20 10-50 parts of carbon black and 10-50 parts of white carbon black, knead for 10 minutes on a roll distance of 3 mm, and finally, add 2 parts of vulcanization accelerator M and 2 parts of vulcanization accelerator CZ into the rubber matrix and knead evenly , under the roller distance of 0.4mm, make a triangular bag 6 times, thin pass, the next sheet, and let stand for 4 hours to obtain the well-mixed unvulcanized water-swellable nitrile rubber for subsequent use.

2) Put the kneaded unvulcanized water-absorbing swellable nitrile rubber in a tableting mold, vulcanize it on a flat vulcanizer at 160°C for 25 minutes (pressure is 10Mpa), open the mold, and take out the vulcanized water-absorbing swellable nitrile Rubber, let stand for 24 hours, and cut the sample. The performance test method of the vulcanized sample is the same as that of the application examples 1-5.

Formulation and test result are shown in Table 3,

 

Each raw material listed in the present invention, as well as the upper and lower limits and interval values of each raw material in the present invention, and the upper and lower limits and interval values of process parameters (such as temperature, time, etc.) can all realize the present invention, and are not listed one by one here. Example.

Claims (4)

1. A rubber-based modification method of water-swellable nitrile rubber, comprising the following steps: after 3g nitrile rubber is completely dissolved with 30mL solvent, it is placed in an ice-water bath, and 0.5～2.5mL of strong After the alkaline solution and 2~10g of hydrogen peroxide solution are stirred and reacted in an ice bath for 1~2.5h, the temperature is raised to 20~50°C, and the reaction is carried out at a constant temperature for 16~36h. After the reaction is completed, the reaction product is adjusted to pH5~6 with an inorganic acidic solution. Then, wash it several times with distilled water, place it in a vacuum drying oven and dry it at 30-40°C to obtain a modified hydrophilic nitrile rubber. The strong alkaline solution is NaOH or KOH with a concentration of 4-6mol/L aqueous solution, the concentration of the hydrogen peroxide solution is 30wt%. 2. The rubber base modification method of water-absorbing nitrile butadiene rubber according to claim 1, characterized in that: said nitrile butadiene rubber is nitrile butadiene rubber with a nitrile content of 30% to 45%, in mole percent. 3. The rubber base modification method of the water-swellable nitrile rubber according to claim 1 or 2, characterized in that: the solvent is THF, acetone, xylene, toluene or chlorobenzene. 4. The rubber-based modification method of water-swellable nitrile rubber according to claim 1 or 2, characterized in that: said inorganic acidic solution is dilute hydrochloric acid aqueous solution.

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