A kind of water-swelling rubber with high interfacial compatibility and preparation method thereof

Abstract

The present invention relates to a high interfacial compatibility water-swelling rubber, which is prepared by mixing and vulcanizing the following materials: 30-60% of styrene-butadiene rubber, 40-70% of styrene-butadiene water-absorbing rubber masterbatch, and 0.6-3.0% of a processing aid. The present invention has the advantages that conventional styrene-butadiene rubber can be used as a raw material, thus avoiding the modification treatment of ordinary styrene-butadiene, the material source is wide, the matrix preparation requirements are not high, and the cost is relatively low. The prepared styrene-butadiene water-absorbing rubber masterbatch effectively weakens the tendency of the water-absorbing resin and the rubber matrix to separate, and improves the interfacial compatibility.

Description

Technical Field

[0001] The invention relates to a water-swelling rubber with high interface compatibility, in particular to a water-swelling rubber with high interface compatibility and a preparation method thereof. Background Art

[0002] Water-absorbent rubber is a new type of functional polymer material that combines the high elasticity and high strength of rubber with the high water absorption of water-absorbent resin. It integrates water absorption and expansion properties, deformability and high strength. It can be used as a functional water-stopping material and is used in construction water plugging, cable waterproofing, drilling leak plugging and other fields.

[0003] In water absorption and water stopping applications, acrylic polymer absorbent resin is one of the most commonly used materials. For example, Chinese patent CN1122051C discloses a method for synthesizing a room temperature polymerized super absorbent resin, which is obtained by graft copolymerization of acrylic acid, starch and bentonite.

[0004] Chinese patent CN102250276A discloses a clay-based zwitterionic hydrophobic salt-resistant superabsorbent resin and a preparation method thereof, which is polymerized from acrylic acid, acrylamide, a cationic monomer, a hydrophobic component and clay, and has high salt resistance and water absorption rate.

[0005] After absorbing water, these polymer materials lose strength and cannot withstand greater pressure. Therefore, their applications are limited in leak plugging in construction and drilling operations.

[0006] The water-swelling rubber prepared by compounding rubber and water-absorbing resin has a certain water-swelling capacity and high strength after absorbing water, which has attracted much attention. Chinese patent CN109666199A discloses a high-strength water-absorbing rubber, wherein the nitrile rubber is firstly quickly refined on a plasticizer, and then calcium oxide, stearic acid, white carbon black, modified bentonite water-absorbing resin and a compatibilizer are added, wherein the water-absorbing resin is polymerized from sodium-based soil and acrylic acid. Mixing is performed for 20-40 minutes, and then sulfur and accelerator DM are added for mixing. After mixing evenly, thin pass is performed, sheets are rolled out, and finally vulcanization is performed. The vulcanization temperature is 135-150°C, and the finished product is obtained by cooling to room temperature after vulcanization.

[0007] Chinese patent CN106046453A discloses a water-swellable nitrile rubber and a preparation method thereof. The rubber is made from nitrile rubber, a water-absorbing resin and a series of additives and can be used as a sealing material.

[0008] Chinese patent CN105949700A discloses a method for preparing water-swellable rubber, which is made by mixing acrylic rubber and polyurethane with additives and vulcanizing them. The operation process is simple and the equipment requirements are low. It has water absorption and water resistance properties, and has good strength and excellent mechanical properties. It can be widely used in the construction field.

[0009] Chinese patent CN104017254B discloses a method for preparing a reaction-expanded nitrile water-swellable rubber, which is processed and mixed with nitrile rubber, water-absorbing resin, and various additives. It can be widely used in tunnels, culverts, swimming pools, basements, underwater projects, underground oil production, water supply facilities, civil construction, etc.

[0010] However, the water-swellable rubber material is formed by blending a hydrophobic nitrile rubber and a hydrophilic water-absorbing resin, and most of the blends are incompatible or partially compatible. For example, patent CN106317530A describes that when this type of water-swellable rubber is used, the water-swellable resin is prone to precipitate from the base rubber, which reduces the water absorption performance, long-term water retention and reusability of the rubber. Summary of the invention

[0011] One of the purposes of the present invention is to provide a water-swellable rubber with high interfacial compatibility.

[0012] The second object of the present invention is to provide a method for preparing the water-swellable rubber with high interfacial compatibility.

[0013] In order to obtain a water-swellable rubber with higher interface compatibility, the present invention pre-prepares a styrene-butadiene water-swellable rubber masterbatch by in-situ polymerization, provides a water-swellable rubber with high interface compatibility, and can enhance the bonding ability between the water-absorbing resin and the matrix styrene-butadiene rubber.

[0014] The water-swellable rubber with high interfacial compatibility of the present invention is characterized in that it is made by mixing and vulcanizing the following materials in the following proportions:

[0015] Styrene butadiene rubber 30-60%

[0016] Styrene butadiene absorbent rubber masterbatch 40-70%

[0017] Processing aids 0.6-3.0%.

[0018] Generally, the styrene butadiene water-absorbing rubber masterbatch is prepared by reverse suspension polymerization of a hydrophilic monomer using liquid styrene butadiene rubber as the oil phase.

[0019] The hydrophilic monomer for preparing the styrene-butadiene water-absorbing rubber masterbatch is a mixture of one of acrylic acid and methacrylic acid and acrylamide.

[0020] The mass ratio of the acrylic monomer to acrylamide is 20-50:50-80.

[0021] The processing aid is composed of a vulcanizing agent, an accelerator and an antioxidant. The vulcanizing agent is sulfur, the accelerator is accelerator CBS, and the antioxidant is RD.

[0022] The mass ratio of the vulcanizing agent, accelerator and antioxidant added to the rubber material is 0.1-1.2%: 0.1-0.5%: 0.4-1.5%.

[0023] The method for preparing the water-swellable rubber of the present invention comprises the following two steps:

[0024] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: prepare a mixed solution of acrylic monomer and acrylamide, add sodium hydroxide to adjust the neutralization degree, add initiator ammonium persulfate and cross-linking agent N'-methylenebisacrylamide, mix and stir evenly, add to liquid styrene-butadiene rubber, add Span 80 as an emulsifier, and add 0.1% vulcanizing agent elemental sulfur, heat to 60-90°C, polymerize for 2-4 hours, heat to 100-120°C and maintain for 1-2 hours to remove moisture and promote slow cross-linking of liquid rubber, after the reaction is completed, cool and cut to obtain styrene-butadiene water-absorbing rubber masterbatch;

[0025] (2) Preparation of water-swellable rubber with high interfacial compatibility: Add styrene-butadiene rubber and styrene-butadiene water-swellable rubber masterbatch into an open mixing mill, then add an antioxidant, a vulcanizing agent, and an accelerator, and mix them; place the mixed styrene-butadiene rubber in a mold, apply pressure on a flat vulcanizer, and vulcanize at 160-200°C. After the vulcanization is completed, open the mold, take it out, cool it down, and cut it to obtain a finished water-swellable rubber product.

[0026] Generally, the neutralization degree is adjusted to 0-80%, and the mass concentration of the initiator ammonium sulfate in the mixed solution is 0.1-1.0%.

[0027] The mass concentration of the cross-linking agent N'-methylenebisacrylamide in the mixed solution is 0.3-2.0%.

[0028] The high interfacial compatibility water-swelling rubber provided by the present invention first prepares a styrene-butadiene water-absorbing rubber masterbatch, the rubber masterbatch adopts the method of reverse suspension polymerization, with a liquid styrene-butadiene rubber with a molecular weight of 2000-15000 as a continuous phase, and under the stabilizing effect of an emulsifier, the polymerization monomer and the initiator solution are uniformly dispersed by high-speed stirring to form fine dispersed particles, and then the temperature is raised to initiate polymerization. During the polymerization process, free radical polymerization is carried out in the dispersed particles, and at the same time, the vulcanizing agent in the continuous phase promotes the vulcanization of the liquid rubber to form a cross-linked network structure with a low degree of crosslinking, and promotes the transformation of the liquid rubber to solid rubber. By high-speed stirring before polymerization, the dispersibility of the monomer solution is improved, the water-absorbing resin particles are more fine and uniform, and the dispersion is stable, avoiding the weakness of the water-absorbing resin being difficult to disperse when directly mixing with raw rubber. In-situ polymerization in rubber improves the compatibility between the water-absorbing resin and the rubber matrix in the masterbatch.

[0029] The invention has the advantages that conventional styrene butadiene rubber can be used as raw material, thus avoiding modification of common styrene butadiene, the material source is wide, the matrix preparation requirements are not high, and the cost is relatively low. The prepared styrene butadiene water-absorbing rubber masterbatch effectively reduces the tendency of separation between the water-absorbing resin and the rubber matrix, and improves the interface compatibility. DETAILED DESCRIPTION

[0030] The present invention is further described below by way of examples, the purpose of which is only to provide a better understanding of the present invention rather than to limit the scope of protection of the present invention.

[0031] Example 1

[0032] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 20 parts by weight of acrylic acid and 80 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 80%, add 0.5% of the solution weight of ammonium persulfate, 0.3% of the crosslinking agent N'-methylenebisacrylamide, stir and dissolve evenly. Take 300 parts by weight of liquid styrene-butadiene rubber, add 0.3 parts by weight of elemental sulfur, 15 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir and disperse at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 60°C for polymerization for 4 hours, and keep stirring to raise the temperature to 120°C to evaporate water under reduced pressure, maintain for 1 hour, cool down to end the reaction, cut to obtain the masterbatch for use.

[0033] (2) Preparation of water-swellable rubber with high interfacial compatibility: 30 parts by weight of styrene-butadiene rubber and 70 parts by weight of styrene-butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.5 parts of antioxidant RD, 0.5 parts of sulfur and 0.3 parts of accelerator CBS, and mixing. The mixed styrene-butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 160°C for 1 hour. After the vulcanization, the mold was opened and the rubber was taken out, cooled and cut to obtain a water-swellable rubber sample.

[0034] Example 2

[0035] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 50 parts by weight of acrylic acid and 50 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 20%, add 0.1% of ammonium persulfate by weight of the solution, 2.0% of crosslinking agent N'-methylenebisacrylamide, stir and dissolve evenly. Take 400 parts by weight of liquid styrene-butadiene rubber, add 0.4 parts by weight of elemental sulfur, 32 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir and disperse at high speed, after dispersion to form a mixed solution, heat to 60°C for polymerization for 4 hours, keep stirring and raise the temperature to 100°C to evaporate water under reduced pressure, maintain for 2 hours, cool down to end the reaction, cut to obtain masterbatch for use.

[0036] (2) Preparation of water-swellable rubber with high interfacial compatibility: 60 parts by weight of styrene-butadiene rubber and 40 parts by weight of styrene-butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by adding 0.4 parts of antioxidant RD, 0.1 parts of sulfur and 0.5 parts of accelerator CBS, and mixing. The mixed styrene-butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 200°C for 10 minutes. After the vulcanization, the mold was opened and the sample was taken out. After cooling, the sample was cut to obtain a water-swellable rubber sample.

[0037] Example 3

[0038] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 30 parts by weight of acrylic acid and 70 parts by weight of acrylamide, add water to dissolve to a concentration of 35%, add 1.0% of the solution weight of ammonium persulfate and 1.0% of the crosslinking agent N'-methylenebisacrylamide, and stir to dissolve evenly. Take 500 parts by weight of liquid styrene-butadiene rubber, add 0.5 parts by weight of elemental sulfur and 25 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 90°C for polymerization for 2 hours, and keep stirring to raise the temperature to 110°C to evaporate water under reduced pressure, maintain for 1.5 hours, cool down to end the reaction, and cut to obtain the masterbatch for use.

[0039] (2) Preparation of water-swellable rubber with high interfacial compatibility: 60 parts by weight of styrene butadiene rubber and 40 parts by weight of styrene butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.0 parts of antioxidant RD, 1.2 parts of sulfur, and 0.5 parts of accelerator CBS, and mixing. The mixed styrene butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 160°C for 40 minutes. After the vulcanization, the mold was opened and the rubber was taken out. After cooling, the rubber was cut to obtain a water-swellable rubber sample.

[0040] Example 4

[0041] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 20 parts by weight of acrylic acid, 10 parts by weight of methacrylic acid and 70 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 40%, add 0.5% of the solution weight of ammonium persulfate, 1.2% of the crosslinking agent N'-methylenebisacrylamide, stir and dissolve evenly. Take 600 parts by weight of liquid styrene-butadiene rubber, add 0.6 parts by weight of elemental sulfur and 40 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir and disperse at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 80°C for polymerization for 3 hours, and keep stirring to raise the temperature to 110°C to evaporate water under reduced pressure, maintain for 1 hour, cool down to end the reaction, cut to obtain the masterbatch for use.

[0042] (2) Preparation of water-swellable rubber with high interfacial compatibility: 50 parts by weight of styrene-butadiene rubber and 50 parts by weight of styrene-butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.3 parts of antioxidant RD, 0.5 parts of sulfur and 0.3 parts of accelerator CBS, and mixing. The mixed styrene-butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 180°C for 30 minutes. After the vulcanization, the mold was opened and the rubber was taken out, cooled and cut to obtain a water-swellable rubber sample.

[0043] Example 5

[0044] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 30 parts by weight of methacrylic acid and 70 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 50%, add 0.5% of the solution weight of ammonium persulfate, 1.2% of the crosslinking agent N'-methylenebisacrylamide, stir and dissolve evenly. Take 1000 parts by weight of liquid styrene-butadiene rubber, add 1 part by weight of elemental sulfur, 50 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir and disperse at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 70°C for polymerization for 4 hours, and keep stirring to raise the temperature to 120°C to evaporate water under reduced pressure, maintain for 1 hour, cool down to end the reaction, cut to obtain the masterbatch for use.

[0045] (2) Preparation of water-swellable rubber with high interfacial compatibility: 50 parts by weight of styrene-butadiene rubber and 50 parts by weight of styrene-butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.5 parts of antioxidant RD, 0.5 parts of sulfur, and 0.3 parts of accelerator CBS, and mixing. The mixed styrene-butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 160°C for 1 hour. After the vulcanization, the mold was opened and the rubber was taken out, cooled, and cut to obtain a water-swellable rubber sample.

[0046] Example 6

[0047] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 40 parts by weight of acrylic acid and 60 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 60%, add 0.5% of the solution weight of ammonium persulfate, 1.2% of the crosslinking agent N'-methylenebisacrylamide, and stir to dissolve evenly. Take 700 parts by weight of liquid styrene-butadiene rubber, add 0.7 parts by weight of elemental sulfur, 35 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 60°C for polymerization for 4 hours, and keep stirring to raise the temperature to 120°C to evaporate water under reduced pressure, maintain for 1 hour, cool down to end the reaction, and cut to obtain the masterbatch for use.

[0048] (2) Preparation of water-swellable rubber with high interfacial compatibility: 60 parts by weight of styrene butadiene rubber and 40 parts by weight of styrene butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.5 parts of antioxidant RD, 0.5 parts of sulfur, and 0.3 parts of accelerator CBS, and mixing. The mixed styrene butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 160°C for 1 hour. After the vulcanization, the mold was opened and the rubber was taken out, cooled, and cut to obtain a water-swellable rubber sample.

[0049] Example 7

[0050] (1) Preparation of styrene-butadiene water-absorbing rubber masterbatch: Take 20 parts by weight of acrylic acid and 80 parts by weight of acrylamide, add water to dissolve to a concentration of 40%, add 30% sodium hydroxide solution to neutralize, adjust the neutralization degree to 80%, add 0.5% of the solution weight of ammonium persulfate, 1.0% of the crosslinking agent N'-methylenebisacrylamide, and stir to dissolve evenly. Take 300 parts by weight of liquid styrene-butadiene rubber, add 0.3 parts by weight of elemental sulfur, 15 parts by weight of Span 80 emulsifier, add the monomer mixed solution to the liquid rubber, heat to 40°C and stir at high speed for 10 minutes, after dispersion to form a mixed solution, heat to 60°C for polymerization for 4 hours, and keep stirring to raise the temperature to 120°C to evaporate water under reduced pressure, maintain for 1 hour, cool down to end the reaction, and cut to obtain the masterbatch for use.

[0051] (2) Preparation of water-swellable rubber with high interfacial compatibility: 30 parts by weight of styrene-butadiene rubber and 70 parts by weight of styrene-butadiene water-swellable rubber masterbatch were added to an open mixing mill, followed by addition of 1.5 parts of antioxidant RD, 0.5 parts of sulfur and 0.3 parts of accelerator CBS, and mixing. The mixed styrene-butadiene rubber was placed in a mold, pressurized on a flat vulcanizer, and vulcanized at 160°C for 1 hour. After the vulcanization, the mold was opened and the rubber was taken out, cooled and cut to obtain a water-swellable rubber sample.

[0052] Example 8

[0053] The water absorption capacity of the prepared water-swelling rubber samples in distilled water and the strength of the water-swelling rubber were measured.

[0054] Method for determining water swelling performance: Take 1.00g of 8-16 mesh granular high interfacial compatibility water swelling rubber sample, add it to 300mL distilled water at room temperature, and after saturation, use filter paper to absorb the mobile water on the surface of the particles, weigh the mass m1 of the sample after water absorption, and calculate the water swelling multiple Q according to the following formula:

[0055] Q=(m 1 -1) / 1.

[0056] The determination of tensile strength and elongation at break shall refer to the method of "GB / T528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0057] The test results are shown in Table 1.

[0058] Table 1 Water absorption and mechanical properties of water-swelling rubber

[0059] sample Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Water absorption multiple 8.25 4.28 4.15 4.86 3.65 4.35 8.66 Tensile strength, MPa 6.6 8.9 8.7 8.1 9.5 8.9 6.4 Elongation at break, % 756 865 850 826 910 872 712

Claims

1. A water-swellable rubber with high interfacial compatibility, characterized in that: It is made by mixing and vulcanizing the following materials: Styrene butadiene rubber 30-60% Styrene butadiene absorbent rubber masterbatch 40-70% Processing aids 0.6-3.0%; The styrene butadiene water-absorbing rubber masterbatch is prepared by reverse suspension polymerization of a hydrophilic monomer using liquid styrene butadiene rubber as the oil phase, wherein the hydrophilic monomer is a mixture of one of acrylic acid and methacrylic acid and acrylamide; The preparation of the styrene butadiene water-absorbing rubber masterbatch comprises the following steps: preparing a mixed solution of one of acrylic acid and methacrylic acid and acrylamide, adding sodium hydroxide to adjust the neutralization degree, adding an initiator ammonium persulfate and a crosslinking agent N,N'-methylenebisacrylamide, mixing and stirring evenly, adding to liquid styrene butadiene rubber, adding Span 80 as an emulsifier, and adding 0.1% vulcanizing agent elemental sulfur, heating to 60-90° C., polymerizing for 2-4 hours, heating to 100-120° C. and maintaining for 1-2 hours to remove moisture and promote slow crosslinking of the liquid rubber, and after the reaction is completed, cooling and cutting to obtain the styrene butadiene water-absorbing rubber masterbatch.

2. The water-swellable rubber with high interfacial compatibility as claimed in claim 1, characterized in that: The processing aid consists of a vulcanizing agent, an accelerator and an antioxidant.

3. The water-swellable rubber with high interfacial compatibility as claimed in claim 1, characterized in that: The mass ratio of one of acrylic acid and methacrylic acid to acrylamide is 20-50:50-80.

4. The water-swellable rubber with high interfacial compatibility as claimed in claim 2, characterized in that: The vulcanizing agent is sulfur, the accelerator is accelerator CBS, and the antioxidant is RD.

5. The water-swellable rubber with high interfacial compatibility as claimed in claim 4, characterized in that: The mass proportions of the vulcanizing agent sulfur, the accelerator CBS and the antioxidant RD are 0.1-1.2%: 0.1-0.5%: 0.4-1.5% respectively.

6. The water-swellable rubber with high interfacial compatibility as claimed in claim 1, characterized in that: The neutralization degree is adjusted to 0-80%, and the mass concentration of the initiator ammonium persulfate in the mixed solution is 0.1-1.0%.

7. The water-swellable rubber with high interfacial compatibility as claimed in claim 1, characterized in that: The mass concentration of the cross-linking agent N,N'-methylenebisacrylamide in the mixed solution is 0.3-2.0%.

8. A method for preparing the water-swellable rubber with high interfacial compatibility as claimed in claim 1, characterized in that: Add styrene butadiene rubber and styrene butadiene water-absorbing rubber masterbatch into an open mill, then add an antioxidant, a vulcanizing agent and an accelerator, and mix; put the mixed styrene butadiene rubber into a mold, pressurize it on a flat vulcanizer, and vulcanize it at 160-200°C. After the vulcanization is completed, open the mold to take it out, and cut it after cooling to obtain a water-absorbing and swelling rubber product.