Method for converting anionic SBR latex into cationic SBR latex

Abstract

The invention discloses a method for converting anionic SBR latex into cationic SBR latex, relates to the field of emulsion polymerization, and aims to solve the problems of complex processing, long production period and high production cost in the prior art, and adopts the technical scheme that a conversion agent prepared by mixing three surfactants BS-12, CAB-35 and NP-10 is added into the anionic SBR latex and uniformly stirred, and then the anionic SBR latex is prepared into the cationic SBR latex. And adding hydrochloric acid and stirring to convert the anion SBR latex into the cation SBR latex. Compared with an existing conventional preparation method and a conversion method, the preparation method has the advantages that the processing process is simple and convenient, the processing cost is low, the cationic SBR latex can be obtained more quickly and conveniently, the yield and the performance of the obtained cationic SBR latex are equivalent to those of the cationic SBR latex obtained in the prior art, the conversion agent and the acid are directly added, the operation is simple and convenient, and the efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of emulsion polymerization, in particular to a method for converting anionic styrene-butadiene rubber (SBR) latex into cationic SBR latex. Background Art

[0002] Since cationic polymer emulsion plays an important role in the charge balance within the system, cationic SBR latex is used in the modification of emulsified asphalt for road engineering. The conventional preparation method of cationic polymer emulsion is to use dodecyl ammonium chloride as an emulsifier. The basic principle is that the monomer forms an emulsion in water with the help of the emulsifier and mechanical stirring, and then the initiator is added to initiate the polymerization of the monomer. During the reaction, the monomer forms beads in the water, and the initiator decomposes in the water phase to produce free radicals, which diffuse into the inside of the beads to initiate the polymerization reaction. During the polymerization process, the monomer inside the beads is continuously consumed, the volume of the beads gradually decreases, and finally polymer particles are formed.

[0003] This method has complicated steps, a long production cycle, low output, and increased production costs.

[0004] In the document "Progress in Research on Cationic Emulsion Polymerization and Its Application", a conversion method is also disclosed, which converts anionic latex into cationic latex by using cationic surfactants and cationic emulsifiers.

[0005] Although this preparation method is simplified in steps and reduces production costs compared to conventional preparation methods, it still has room for further improvement. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the existing defects and provide a method for converting anionic SBR latex into cationic SBR latex, which can effectively solve the problems in the background technology.

[0007] In order to achieve the above object, the present invention discloses a method for converting anionic SBR latex into cationic SBR latex, and the technical scheme adopted is comprising the following steps:

[0008] Step 1, weigh each raw material by weight,

[0009] Anionic SBR latex 90%~83%

[0010] Conversion agent 3%~7%

[0011] Acid 7% to 10%;

[0012] Step 2, adding the conversion agent to the anionic SBR latex, stirring evenly, to obtain an intermediate product;

[0013] Step 3, adding acid to the intermediate product obtained in step 2, and stirring evenly to obtain a uniform and stable cationic SBR latex.

[0014] Under acidic conditions, anionic SBR latex can be converted into cationic SBR latex by a conversion agent.

[0015] As a preferred technical solution of the present invention, the conversion agent is a zwitterionic surfactant with a concentration of 65%, which is a mixture of three surfactants: BS-12, CAB-35, and NP-10.

[0016] As a preferred technical solution of the present invention, the acid is hydrochloric acid.

[0017] As a preferred technical solution of the present invention, in step 2 and step 3, mechanical stirring is used for stirring, the stirring speed is 400-600 rpm, and the stirring time is 0.5-1 h in each step, so that the anionic SBR latex, the conversion agent and the acid are fully mixed.

[0018] Compared with the prior art, the invention has the following beneficial effects: the invention realizes the conversion of the anionic SBR latex into the cationic SBR latex by sequentially adding a conversion agent composed of a surfactant and an acid into the anionic SBR latex and stirring them uniformly; compared with the existing conventional preparation method and conversion method, the preparation method has a simple processing process and a low processing cost, and can obtain the cationic SBR latex faster and more conveniently; the yield and performance of the obtained cationic SBR latex are equivalent to those obtained in the prior art; the conversion agent and the acid are added in a direct adding manner, and the operation is simple and efficient. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example 1

[0021] This embodiment discloses a first implementation mode of the present invention, and the adopted technical solution is to include the following steps:

[0022] Step 1, weigh each raw material by weight,

[0023] Anionic SBR latex 90%

[0024] Conversion agent 3%

[0025] Hydrochloric acid 7%;

[0026] The conversion agent is a mixture of three surfactants: BS-12, CAB-35, and NP-10, with a concentration of 65%;

[0027] Step 2, adding the conversion agent to the anionic SBR latex, stirring with a paddle stirrer at a stirring speed of 600 rpm for 0.5 h, and stirring evenly to obtain an intermediate product;

[0028] Step 3, adding hydrochloric acid to the intermediate product obtained in step 2, stirring with a paddle stirrer at a stirring speed of 600 rpm for 0.5 h, and after stirring evenly, obtaining a uniform and stable cationic SBR latex.

[0029] Example 2

[0030] This embodiment discloses a second implementation of the present invention, and the technical solution adopted is to include the following steps:

[0031] Step 1, weigh each raw material by weight,

[0032] Anionic SBR latex 83%

[0033] Converter 7%

[0034] Hydrochloric acid 10%;

[0035] The conversion agent is a mixture of three surfactants: BS-12, CAB-35, and NP-10, with a concentration of 65%;

[0036] Step 2, adding the conversion agent to the anionic SBR latex, stirring with a paddle stirrer at a stirring speed of 400 rpm for 1 hour, and stirring evenly to obtain an intermediate product;

[0037] Step 3, adding hydrochloric acid to the intermediate product obtained in step 2, stirring with a paddle stirrer at a stirring speed of 400 rpm for 1 hour, and after stirring evenly, obtaining a uniform and stable cationic SBR latex.

[0038] Example 3

[0039] This embodiment discloses a third implementation mode of the present invention, and the technical solution adopted is to include the following steps:

[0040] Step 1, weigh each raw material by weight,

[0041] Anionic SBR latex 87%

[0042] Conversion agent 5%

[0043] Hydrochloric acid 8%;

[0044] The conversion agent is a mixture of three surfactants: BS-12, CAB-35, and NP-10, with a concentration of 65%;

[0045] Step 2, adding the conversion agent to the anionic SBR latex, stirring with a paddle stirrer at a stirring speed of 500 rpm for 0.75 h, and stirring evenly to obtain an intermediate product;

[0046] Step 3, adding hydrochloric acid to the intermediate product obtained in step 2, stirring with a paddle stirrer at a stirring speed of 500 rpm for 0.75 h, and after stirring evenly, obtaining a uniform and stable cationic SBR latex.

[0047] Comparative Example 1: Conventional emulsion synthesis method

[0048] Step a, after mixing butadiene, styrene and a cationic emulsifier, heating in a water bath to 85° C. in an acidic environment with a pH of 4, and maintaining the mixture for 2 hours, stirring and adding a stabilizer during the heating process;

[0049] Step b, after cooling the intermediate product obtained in step a, continue to heat it under negative pressure and 75° C. for 2 hours to obtain a cationic styrene-butadiene emulsion.

[0050] Comparative Example 2: Conversion Method

[0051] Step A, diluting the styrene-butadiene rubber anionic emulsion to 30%;

[0052] Step B, stirring a 30% concentration of a cationic surfactant using a stirrer at a speed of 600 rpm;

[0053] Step C, adding the anionic dilute latex obtained in step A to the cationic surfactant in step B, and stirring continuously for 2 hours;

[0054] Step D, add acid to the mixture obtained in step C to adjust the pH, and continue stirring for 2 hours.

[0055] The preparation process and finished product performance of Example 1 were compared with those of Comparative Examples 1 and 2, and the results are as follows:

[0056]

[0057] The comparative example 2 obtains a dilute latex, which is generally not used for the modification of emulsified asphalt for road engineering. Through the above comparison, it can be seen that the preparation time of Example 1 is shorter than that of Comparative Examples 1 and 2, the preparation operation is less, and it is more convenient. The performance of the final product is equivalent to that of the product obtained in Comparative Example 1.

[0058] The conversion agent in this article is a product available on the market and belongs to the prior art.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for converting anionic SBR latex into cationic SBR latex, characterized in that: The following steps are involved: Step 1, weigh each raw material by weight, Anionic SBR latex 90%~83% Conversion agent 3%~7% Acid 7%~10%; The conversion agent is a mixture of three surfactants: BS-12, CAB-35 and NP-10; Step 2, adding the conversion agent to the anionic SBR latex, stirring evenly, to obtain an intermediate product; Step 3, adding acid to the intermediate product obtained in step 2, and stirring evenly to obtain a uniform and stable cationic SBR latex.

2. The method for converting anionic SBR latex into cationic SBR latex according to claim 1, characterized in that: The concentration of the conversion agent is 65%.

3. The method for converting anionic SBR latex into cationic SBR latex according to claim 1, characterized in that: The acid is hydrochloric acid.

4. The method for converting anionic SBR latex into cationic SBR latex according to any one of claims 1 to 4, characterized in that: In step 2 and step 3, mechanical stirring is used for stirring, the stirring speed is 400-600 rmp, and the stirring time is 0.5-1 h in each step.

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